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In light of Vietnam's significant role as a top ten seafood exporter, particularly in shrimp and catfish, the COVID-19 pandemic has disrupted the nation's crucial seafood production and exports since early 2020. Our investigation, which is based on farmer surveys and enterprise interviews, has revealed a significant increase in production costs, especially in intensive shrimp farming, which has had a greater impact on compared to semi-intensive farming. Approximately 51.6% of farmers reported a strong effect on feed expenses, with 39.6% categorizing it as a very strong effect. This represents a significant impact on input costs, primarily due to challenges in sourcing materials, particularly feed, which constitutes the highest proportion of production costs. Challenges in goods exchange along the supply chain were strongly reported by 75% of enterprises, with 25% describing them as very strong, thus affecting production costs and inventory. Labor costs have also increased due to COVID-19, with 25% reporting a strong influence and 75% indicating a stable impact. The pandemic has affected commercial pangasius prices, with 29.7% of respondents noting a decrease and 41.8% confirming increased raw material costs, especially for fish feed. Feed costs account for 85.6%, while seed costs comprise 5.1% of total expenditure. Supply chain disruptions have led to enterprises having to suspend operations or reduce operating capacity to 30–40% due to a shortage of workers. The paper suggested practical management and technical solutions, emphasizing the need for supportive policies and a government-led mechanism to assist workers. This study offers valuable insights into the industry's resilience and adaptive mechanisms to face post-pandemic challenges. [ABSTRACT FROM AUTHOR]

The genetic variabilities in internal transcribed spacers ITS1 and ITS2 of rDNA are explored to a limited extent in vertebrates including fish species. This study explores unique molecular signature in these spacers from multiple catfish species from the order siluriformes. Supporting the concerted evolution, both ITS1 and ITS2 were found prevalent with microsatellite and random repeats, with diverse distribution in each species in terms of nucleotide composition, their position and length, giving a species-specific impression in repeats. Their secondary structures too have shown distinct structural homology with variations in helix lengths, loops, and non-canonical base pairs, where ITS2 4-helix carries additional nine conserved motifs while that of ITS1 was found highly branched with multiple sub-branching unique to each species and a long tail helix common in all. This combination of secondary structures and repeats have formed unique molecular signatures distinguishing each catfish species. Since the evolutionary and maturation biology of rDNA is similar in vertebrates, these molecular signatures in internal spacers could effectively contribute to the molecular characterization across the diverse group of catfish species. [ABSTRACT FROM AUTHOR]

A newly isolated rhabdovirus-like agent, named SHRV-In, obtained from snakehead fish in India was further characterized in this study. The virus demonstrated growth in various cell lines including those derived from snakehead and seabass species. It exhibited sensitivity to acidic conditions (pH 3.0) and exposure to 56 °C. Five structural proteins of 20 to 68 kDa were found in the purified virus. Experimental infection trials conducted on catfish (Pangasius pangasius) resulted in mortality 72 h post-infection, whereas no mortality was observed in rohu (Labeo rohita) and common carp (Cyprinus carpio) fingerlings. Molecular characterization of the virus involved sequencing of the N, P, M, and G gene fragments after PCR amplification using specific primers. Sequence analysis of all four viral genes showed high similarity with the previously isolated snakehead rhabdovirus (SHRV) from Thailand. Phylogenetic analysis and gene sequence alignment placed the SHRV-In isolate within the Novirhabdovirus group, which includes viruses like VHSV (viral hemorrhagic septicemia virus), IHNV (infectious hematopoietic necrosis virus), and SHRV. However, our repeated trials failed to amplify the NV gene in this isolate SHRV-In. [ABSTRACT FROM AUTHOR]

Branchiura are a crustacean parasite widely known around the world as fish lice. In South America, they have been most studied in Brazil as with high levels of infestation, the parasites can be harmful to the health of fish and cause economic losses in fish farms. The objective of the present study is to provide, for the first time, significant information about the parasitic indices, infestation sites, and morphology of Dolops carvalhoi, and to report the appearance of a new host in the Amazon region of Peru. A total of 24 specimens of Colossoma macropomum, Piaractus brachypomus, and Calophysus macropterus from fish farms were individually analyzed to identify the presence of the ectoparasites. The Branchiura collected from the body surfaces of the fish were separated according to sex, the parasitic indices were calculated, and the parasites were clarified in 90% lactic acid for taxonomic identification. They were also preserved in 2.5% glutaraldehyde, and dehydration and critical point procedures were applied by scanning electron microscopy to visualize the detailed structures. The taxa identified was D. carvalhoi, which had a prevalence of 64.7%, a mean intensity of 1.6, and a mean abundance of 1 parasite/fish in C. macropterus; a prevalence of 100%, a mean intensity, and mean abundance of 2.8 parasites/fish in P. brachypomus; and a prevalence of 100%, but a mean intensity and mean abundance of 15 parasites/fish in C. macropomum. The pectoral and dorsal fins and the urogenital opening had the highest occurrence of D. carvalhoi in the host. Dolops carvalhoi has sexual dimorphism, and we reported for the first time the infestation of this parasite in leather fish C. macropterus. [ABSTRACT FROM AUTHOR]

As an important contributor to Louisiana’s economy, the commercial freshwater fisheries have been the subject of growing attention in recent years by resource managers as the industry appears to be on the brink of collapse. Fewer participants are entering the field, fish buyers and processors are closing, and market prices remain stagnant. To better understand this industry, we conducted a study to characterize the commercial freshwater fisheries in Louisiana including the fishermen, the fishing operations, the effort across the state, local knowledge on management issue and barriers and opportunities for the future of the industry. We completed structured interviews at fish houses across Louisiana. The average full-time fisherman was 56 years old with about 34 years of commercial fishing experience, and catfish (Ictaluridae spp.) and buffalo (Ictobius spp.) appear to be the most sought-after finfish; however, this slightly differs by region. Overall, this study provides in-depth insight into the trends, problems, and successes of Louisiana’s freshwater commercial fisheries. This information will allow managers and other groups like cooperative extension to identify and design opportunities for the industry and utilize their information in management across the state. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effects of heat stress and black sand acute exposure on the erythron profile, hematological and antioxidant parameters, as well as histological and histochemical indices. Catfish were subjected to black sand nanoparticles (6.4 g of nanoparticles black sand per kg of diet), thermal stress (32 °C), and a combined treatment involving both stressors over a period of 15 days. Catfish exposed to black sand nanoparticles and heat stress singly and/or in combination showed significantly lower red blood cells (RBCs) count, hemoglobin (Hb), platelets, white blood cells (WBCs) count, large lymphocytes, small lymphocytes, and monocytes. Antioxidant indices decreased in black sand NPs and heat stress combination compared to other groups. Notably, the combination of black sand nanoparticles and heat stress led to a substantial increase in the percentages of both RBCs alterations and nuclear abnormalities. Histological examinations of the liver revealed various features, including intracellular bleeding, cytoplasmic vacuolation, tissue deterioration, hepatocyte pyknotic nuclei, nuclear displacement, shrinkage, and accumulation of melanomacrophage cells. In conclusion, the study underscores that the effects of black sand nanoparticles on erythron profile, hematological and antioxidant parameters, as well as histological and histochemical indices, become more pronounced under elevated temperatures indicating the potential for synergistic effects between pollution and climate change. This holistic approach is crucial for developing more accurate forecasts of the complex interactions between environmental stressors and their implications for aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate propofol as an anesthetic and its effects on physiology and histology in Ictalurus punctatus. To determine the ideal concentration, juvenile of I. punctatus (96.60 ± 27.70 g) were used, submitted to different concentrations of the anesthetic: 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, and 6.0 mg L−1. The concentration evaluated as ideal was 2.5 mg L−1. To evaluate the physiological and histological effects of propofol exposure, juvenile of I. punctatus (99.71 ± 26.38 g) were sampled immediately (T0) and 30 min after anesthesia (T30) with 2.5 mg L−1, had blood, liver, and gill samples collected. The exposure of the animals to propofol in both treatments (T0 and T30) caused increases in plasma glucose and lactate levels (p < 0.05) but prevented an increase in cortisol (p > 0.05). The histological study showed mild to moderate changes in the gills (congestion in the lamellar vessels and central vein and epithelial elevation) and moderate and severe changes in the liver (congestion and degeneration). This study concludes that the concentration of 2.5 mg L−1 of propofol provides safe anesthesia for I. punctatus and prevents increased plasma cortisol levels. [ABSTRACT FROM AUTHOR]

The cyclopoid family Bomolochidae Burmeister, 1835 is one of the most common groups of parasitic copepods infesting fish worldwide. Currently, about 165 species of this family have been reported in marine ecosystems but only a few occur on fish of the family Ariidae Bleeker. During a survey of marine catfish in the Brazilian Amazon Coast, a new species of Boylea Cressey, 1977 was found in the gill chambers of the Thomas sea catfish Notarius grandicassis (Valenciennes) (type-host), Pemecou sea catfish Sciades herzbergii (Bloch) and Coco sea catfish Bagre bagre (Linnaeus) (Siluriformes: Ariidae) off Maranhão Island, State of Maranhão. Boylea inflata sp. nov. can be distinguished from its closest congeners mainly because it has the anterior part of the prosome inflated, the second endopodal segment of leg 3 with one seta and by having a simple outer distal seta on the caudal rami. In addition, an amendment in the diagnosis of Boylea is provided based on the characters present in the new species. Other species of parasitic copepods previously collected from ariid fish off Brazil were revisited and discussed. The present study is the first report of a bomolochid parasitizing the three host species analyzed here, as well as the first report of Boylea in the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

In Egypt, while many studies have focused on the radiometry and mineralogy of black sands, research on their effects on nearby aquatic organisms is rare. This study aimed to assess the combined effects of heat stress (HS) and black sand nanoparticles (BS-NPs) on renal function, antioxidant responses (TAC, SOD, CAT), neuro-stress indicators (AchE, cortisol), and to conduct histopathological investigations in the kidney and spleen tissues of African catfish Clarias gariepinus over a 15-day period to exposure to control, HS (32 °C), BS (6.4 g/kg diet) and HS + BS groups. The outcomes revealed that thermal stress alone showed no significant difference from the control. However, creatinine and uric acid levels were significantly higher in the BS-NPs and HS + BS-NPs groups (p < 0.001). Antioxidant markers (TAC, SOD, and CAT) were substantially reduced across all treated groups (0.05 ≥ p < 0.0001). AchE levels were significantly elevated in BS-NPs and HS + BS-NPs (p < 0.001), while cortisol levels were higher in these groups but not significantly different in HS. Degeneration and necrosis in the white and red pulps, scattered lymphocytes, and increased collagen fiber surrounding blood vessels and the lining of the ellipsoid structure were all evident in the spleen, along with the enlargement of the melanomacrophage centers with big granular, irregular, and brown pigments (hemosiderin). Our study, therefore, provides new insights into how heat stress, an abiotic environmental factor, influences the toxicity of black sand nanoparticles in catfish. [ABSTRACT FROM AUTHOR]

This study aimed to isolate and identify pathogenic bacteria in the intestinal tract, skin, and muscles of Sciades herzbergii; detect histopathological changes in the gill and liver; and use these biomarkers for the assessment of potential risks to human health. Fish were sampled during the rainy and dry seasons at two points in São Marcos Bay, Maranhão, Brazil: Ilha dos Caranguejos (IC) and Porto Grande (PG). Isolation and quantification were carried out using COLItest®. Colonies were subjected to identification and phenotypic investigation of antimicrobial resistance using Vitek®. Gill and liver samples were subjected to routine histological examination. The results indicated the presence of Klebsiella pneumoniae and Escherichia coli, the latter of which showed phenotypic resistance to norfloxacin and gentamicin. Fish caught at PG exhibited more extensive gill and liver damage than fish caught at IC. The findings suggest that histological changes in target organs of S. herzbergii may be influenced by infection with pathogenic bacteria. [ABSTRACT FROM AUTHOR]

In this study, effect of different stocking densities on growth, oxidative stress, antioxidant enzymes, and hematological and immunological values in European catfish (Silurus glanis) was examined. The control (0.06 kg fish/L) and trial (T) 1 (0.08 kg fish/L), T2 (0.10 kg fish/L), and T3 (0.12 kg fish/L) stocking groups were used. Each stocking group with three replicates was carried out in a tank at 22 ± 2 °C water temperature. The fish were fed three times daily for 60 days. The highest final weight (123.3–171.6 g), weight gain (84.13–159.6%), specific growth rate (1.40–2.66%), feed intake (138.5–178.2 g/fish), and feed conversion rate (1.12–1.65%) were provided from the control and T1 stockfish (p > 0.05), followed by the T2 and T3 stockfish (p < 0.05), respectively. The lowest oxidant level and the highest reduced glutathione level and superoxide dismutase, catalase, and glutathione peroxidase activities were obtained from the control fish, followed by the T1, T2, and T3 stockfish, respectively (p < 0.05). In addition, parallel to the increase in stocking density, the erythrocyte count, hematocrit, hemoglobin, erythrocyte volume, corpuscular hemoglobin, and corpuscular hemoglobin concentration values of fish increased (p < 0.05), but the leukocyte count, nitroblue tetrazolium activity, total protein, and immunoglobulin-M values decreased (p < 0.05). The high stocking densities caused oxidative stress in fish, negatively affecting their health and growth and feed evaluation values. However, the stocking density could increase to 0.08 kg/L from 0.06 kg/L in the European catfish fingerling reared in the recirculating aquaculture system by maintaining the water quality and applying good care and feeding. [ABSTRACT FROM AUTHOR]

Catfishing is a form of online deception where an individual presents themselves as an identity that is not their own. The study reported in this article explored the motivations for catfish perpetrators and the impacts on those who had been catfished in terms of the emotions and feelings expressed by victims. Data was collected using the crowd-sourced question and answer website Quora [1] and analysis was conducted on a pre-existing corpus of data which contained participant's answers to questions on catfishing. An automated linguistic analysis using Linguistic Inquiry and Word Count (LIWC-2022 [2]) and a thematic analysis (Braun and Clarke in Qual Res Psychol 3:77–101, 2006 [38]) were conducted on participant's descriptions of their perceptions of the motivations of catfishes and their catfishing experiences. The thematic analysis indicated that the motivations of catfish perpetrators can be linked to entertainment, emulating an ideal self, desiring meaningful interaction, and financial gain. Six emotions and feelings emerged from the accounts of catfishing victims: suspicion, love, depression, anger, embarrassment, and stupidity. These findings contribute to an understanding of what motivates individuals to catfish and suggests further research to explore specific emotions and feelings that catfish victims experience. The LIWC analysis and language style matching analysis showed that the data collected was mostly personal to each individual and that there were similarities in how victims write about their experiences. Therefore, we suggest that LIWC has promise as a method of providing added context to qualitative data analysis methods. [ABSTRACT FROM AUTHOR]

Thermal pollution creates substantial challenges that alter energy demand and produce reactive oxygen species that damage fish DNA, proteins, and lipids. Rhamdia voulezi is a species of fish native to the Iguaçu river, Paraná, Brazil, that does not have scientific records of minimum (CTmin) and maximum (CTmax) temperatures required for survival. As it is a top predator species in the food chain and lives at temperatures below 22 °C, the loss of the species can cause functional problems in controlling the ecosystem and energy flow. The study evaluated the tissue metabolism of the brain, heart, and muscle of R. voulezi (n = 72) subjected to acute thermal stress of 31 °C for 2, 6, 12, 24, and 96 h after acclimatization to 21 °C. The biochemical markers SOD, GPx, MDH, HK, and CK of the brain, PCO of the heart and CAT, glycogen, G6PDH, and ALT of muscle were significant. PCA, IBR, thermal sensitive, and condition factor suggested that R. voulezi has different physiological strategies for acclimatization to 31 °C to mobilize and sustain the metabolic needs of oxygenation and energy allocation/utilization for tissue ATP production. [ABSTRACT FROM AUTHOR]

Photoperiod manipulation is emerging as an effective approach for regulating physiological functions in fish. This study aimed to assess the impact of photoperiod on the growth performance, haematological responses, and economic returns of the endangered and highly valued Indian butter catfish, Ompok bimaculatus. Fish with an average body weight of 28.60 ± 4.78 g were randomly placed in six FRP tanks, each measuring 120 × 45 × 60 cm3. Each tank contained 20 fish exposed to a light intensity of 1500 lx under different photoperiods [24:0 light: dark (L: D), 15 L: 9D, 12 L: 12D, 9 L: 15D, 0 L: 24D and a natural photoperiod (control)], and fed at a daily rate of 2% of their body weight twice daily for 60 days. The fish in the 15 L: 9D photoperiod exhibited the highest final weight (g), percentage weight gain, specific growth rate (SGR) and survival rate, while the lowest was displayed in 24 L: 0D photoperiod group. The feed conversion ratio (FCR) was at its lowest in the catfish subjected to the 15 L: 9D photoperiod. Regarding haematological parameters, the 15 L: 9D photoperiod group showed higher total erythrocyte count, total leukocyte count, haemoglobin levels, and haematocrit values compared to the other groups. Conversely, the 0 L: 24D group, which experienced prolonged darkness, exhibited the lowest values in these parameters. Moreover, the 24 L: 0D, 9 L: 15D, and 0 L: 24D groups displayed a lower mean corpuscular volume (MCV) but higher mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) when compared to the control group. The economic analysis revealed that O. bimaculatus reared in a moderate photoperiod (15 L: 9D) displayed better growth, feed utilization, and overall health. This finding suggests that adopting a 15 L: 9D photoperiod can lead to enhanced production and improved economic returns for farmers culturing this high-value catfish in the future. [ABSTRACT FROM AUTHOR]

Catfish are a highly diverse group of fish that are found in various regions across the globe. The significance of catfish culture extends to various aspects, including food security, economic advancement, preservation of cultural legacy, and ecological stewardship. The catfish industry is presently encountering unprecedented challenges as a consequence of the variability in water temperature caused by climate change. Temperature is a significant abiotic component that regulates and restricts fish physiology throughout their life cycle. The impact of severe temperatures on various species of catfish is dependent upon the magnitude of the stressor and additional influencing factors. This paper presents an analysis of the effects of temperature fluctuations on various aspects of catfish species, including growth and survival, blood parameters, enzymatic and hormone response, oxygen consumption rates, sound generation and hearing skills, nutritional requirements, and other phenotypic attributes. While this review is certainly not exhaustive, it offers a broad synopsis of the ideal temperature ranges that are most favorable for several catfish species. In-depth research to investigate the interacting impacts of severe temperature occurrences in conjunction with other associated environmental stresses on a wider variety of catfish species is crucial in order to further our understanding of how catfish species will respond to the anticipated climate change in the future. [ABSTRACT FROM AUTHOR]

Exposure to high temperatures induces changes in fish respiration, resulting in an increased production of reactive oxygen species. This, in turn, affects the enzymatic and non-enzymatic components of antioxidant defenses, which are essential for mitigating cellular stress. Rhamdia voulezi, an economically important fish species endemic to Brazil's Iguaçu River, served as the subject of our study. Our goal was to assess enzymatic antioxidant biomarkers (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, glucose-6-phosphate dehydrogenase), non-protein thiol levels (reduced glutathione), and markers of oxidative damage (lipoperoxidation and carbonylation) in the liver, gills, and kidneys of R. voulezi after acute exposure to high temperatures (31°C) for 2, 6, 12, 24, and 96 h. Control groups were maintained at 21°C. Our findings revealed that the liver exhibited increased superoxide dismutase levels up to 12 h and elevated glutathione S-transferase levels at 12 and 96 h at 31°C. In the gills, superoxide dismutase levels increased up to 24 h, along with increased lipoperoxidation at 2, 6, 12, and 96 h of exposure to high temperatures. The kidneys responded to heat stress at 12 h, with an increase in superoxide dismutase and catalase activity, and lipid peroxidation was observed at 2 and 6 h at 31°C. The three tissues evaluated responded differently to heat stress, with the liver demonstrating greater physiological adjustment to high temperatures. The intricate interplay of various antioxidant defense biomarkers and oxidative damage suggests the presence of oxidative stress in R. voulezi when exposed to high temperatures. [ABSTRACT FROM AUTHOR]

Coastal river systems provide essential habitats for a diversity of fish species that transition marine, estuarine, and freshwater environments to complete their lifecycles. Movement among and within these environments is important to access resources that optimise growth, survival, and reproduction. Knowledge on the movements, including the drivers, underpins management strategies, although this information is often lacking for many species. We used acoustic telemetry to quantify the relative importance of a range of abiotic stimuli in relation to seasonal movement patterns in blue salmon catfish Neoarius graeffei throughout an unregulated coastal river catchment, the Clarence River in northern New South Wales, Australia. Neoarius graeffei continuously occupied the Clarence River system for the duration of the 1-year study and were mostly confined to estuarine reaches, with occasional movement into freshwater habitats. Seasonal differences in habitat occupation were observed, with N. graeffei using habitats close to the river mouth in winter and upstream estuary habitats in spring. Broad-scale movement patterns were influenced by both water temperature and river flow, and high-flow events (> 1.5 m) resulted in short-term changes (~ 10 days) in habitat use. Sex-specific differences in seasonal habitat use were also observed which we hypothesise is linked to contrasting energetic investment in reproduction. The response of N. graeffei to changes in river flow highlights the need for assessment on these impacts for estuarine-dependent species more broadly, in the face of climate change and increased river regulation. [ABSTRACT FROM AUTHOR]

Commercial aquaculture production of channel catfish (Ictalurus punctatus) occurs in shallow ponds with daily cycling of dissolved oxygen concentration ranging from supersaturation to severe hypoxia. Once daily minimum dissolved oxygen concentration falls below 3.0 mg O2/L, channel catfish have a reduced appetite, leading to reduced growth rates. In other fishes, upregulation of the neuropeptides corticotropin-releasing factor (CRF) and urotensin I (UI) have been implicated as initiating the mechanism responsible for decreasing appetite once an environmental stressor is detected. Channel catfish maintained at 27 °C in aquaria were subjected to varying durations and patterns of hypoxia (1.75 ± 0.07 mg O2/L) to evaluate underlying physiological responses to hypoxia and determine if hypothalamic CRF and UI are responsible for hypoxia-induced anorexia in channel catfish. During a short exposure to hypoxia (12 h), venous Po2 was significantly lower within 6 h and was coupled with an increase of hematocrit and decrease of blood osmolality, yet all responses reversed within 12 h after returning to normoxia. When this pattern of hypoxia and normoxia was repeated cyclically for 5 days, these physiological responses repeated daily. Extended periods of hypoxia (5 days) resulted in similar hematological responses, which did not recover to baseline values during the hypoxia exposure. This study did not find a significant change in hypothalamic transcription of CRF and UI during hypoxia challenges but did identify multiple physiological adaptive responses that work together to reduce the severity of experimentally induced hypoxia in channel catfish. [ABSTRACT FROM AUTHOR]

The present study was executed to evaluate the effect of photoperiod on serum biochemical parameters (glucose, cortisol, ALT, AST and LDH), electrolytic balance (Sodium and potassium), acute phase response (CRP) and histopathology (liver, kidney and skin) of an endangered high valued catfish, Ompok bimaculatus. Catfish (21.00 ± 1.53 cm and 30.00 ± 2.31 g) from the acclimatized stock were randomly distributed to six 120 × 45 × 60 cm3 FRP tanks (n = 20 fish per tank) and exposed to 1500 lx light intensity under different photoperiods [24:0 light: dark (L: D), 15L: 9D, 12L: 12D, 9L: 15D, 0L: 24D and a natural photoperiod (control)], and fed at a daily rate of 2% of bodyweight, twice a day for 60 days. Serum glucose, cortisol and enzymes including aspartate transaminase (AST), lactate dehydrogenase (LDH), alanine transaminase (ALT), and acute phase reactant, such as C-reactive protein (CRP) increased significantly (P < 0.05) in continuous light (24L: 0D), continuous dark (0L: 24D) and short day (9L: 15D) photoperiods, whereas in 15L: 9D and 12L:12D photoperiods, those were in decreasing trend. Serum electrolytes, i.e. potassium level was elevated and sodium level was declined in 24L: 0D, 0L: 24D and 9L: 15D photoperiod groups. Moreover, significant histological alterations in the liver, kidney and skin tissue were also evidenced in the experimented catfish. Typical polygonal hepatocytes with normal blood vessels in liver and normal organization of kidney were seen in catfish of 15L: 9D group. Histological analysis of other groups displayed nuclear degeneration, karyorrhexis, karyolysis, melanomacrophages, nuclear hypertrophy, sinusoid dilation and vacuolar degeneration in liver and hyaline droplets accumulation, granular degeneration, fragmentation of glomerulus and focal necrosis of epithelial cells in kidney. Additionally, general structure of the skin was observed in control group as well as in 15L: 9D group. Contrarily, in 24L: 0D group increased number of mucous cells and vacuoles was observed in the skin of butter catfish. In 9L: 15D and 0L: 24D photoperiods, O. bimaculatus exhibited ruptured epithelial cells, enlarged alarm cells, fat cells, necrotic cells and vacuoles in the skin tissue. The present study depicted that 15L: 9D photoperiod can induce better health of catfish, O. bimaculatus, which, in turn, can help farmers to increase the production of this high valued catfish in future. [ABSTRACT FROM AUTHOR]

Our study helps to evaluate the immune response, antioxidative status, and resistance against heat stress (HS) in Clarias gariepinus treated with propolis extraction; the results will contribute to theories of fish physiology and immunity under high-temperature conditions. Forty-five fish were divided into three equal groups: the control, the HS group at 36 °C, and the HS treated with alcoholic extraction of propolis that dissolved in water for 3 weeks. The results of our study suggested that the stress response differs among tissues thymus, spleen, and liver. All the tissues showed alteration in morphological and cytological structure at the light microscope (LM) and transmission electron microscope (TEM); thymus showed edema and thymocyte destruction; the spleen detected collagen deposition, and the liver displayed endoplasmic reticulum amplification (ER). In addition, we examined oxidative stress and antioxidant defenses (lipid peroxidation, catalase, and glutathione) of the spleen and measured blood biochemical parameters (alanine transaminase and aspartic transaminase levels) after heat stress. However, this toxic effect of HS was neutralized by the propolis extraction. To conclude, propolis is recommended to cope with the impacts of heat stress on catfish (Clarias gariepinus) by improving immunity and antioxidative resistance. [ABSTRACT FROM AUTHOR]

The two gonadotropins, FSH and LH, stimulate growth and development of the gonads through gonadal biosynthesis of steroid hormones and growth factors. To date, cDNA sequences encoding gonadotropin subunits have been isolated and characterized from a large number of fish species. Recently, we successfully cloned and characterized gonadotropins (LHβ, FSHβ, and GPα) from the pituitary glands of the catfish, Heteropneustes fossilis. In the present study, we describe herein the production of recombinant stinging catfish, H. fossilis (hf) FSH (rhfFSH) and LH (rhfLH) using the methylotrophic yeast P. pastoris expression system. We further explored the hypothesis that the recombinant gonadotropins can modulate the hypothalamus-pituitary-ovarian (HPO) axis genes (avt, it, gnrh2, kiss2, and cyp19a1a) and regulate their transcriptional profile and steroid levels in relation to their annual developmental stage during preparatory and pre-spawning phases under in-vitro conditions. We found that the different concentrations of recombinant rhfFSH and rhfLH significantly stimulated E2 levels in the preparatory and prespawning season, and also upregulated gonadal aromatase gene expression in a dose dependent manner. Our results demonstrate that the yeast expression system produced biologically active recombinant catfish gonadotropins, enabling the study of their function in the catfish. [ABSTRACT FROM AUTHOR]

Freshwater rivers are considered the major route for microplastics (MPs), yet limited studies have been reported on MPs in freshwater river fish, especially in Bangladesh. This research reveals the intake of MPs by the giant river catfish Sperata seenghala, collected from the Meghna River, which is the only outlet of the Ganges-Brahmaputra River. Three locations, namely, Chandpur Sadar, Bhola Sadar, and Char Fasson, along the Meghna River, were selected in order to investigate the gastrointestinal tracts (GIT) of the fish. Ninety percent (n=27) of fish (n=30) were contaminated, with fragment-shaped MPs (65%) as the most abundant among the four types. A total of 179 MP particles were detected using micro-Fourier transformed infrared spectroscopy (μ-FTIR), with an average of 5.96 ± 1.32 MP particles per fish. Among the four size groups, the highest proportion of MPs (54%) occurred in the 45–100 μm group; the dominant color among the seven color groups was white (30%). The highest quantity of MPs was found in the relatively densely populated Chandpur Sadar region. Polypropylene-polyethylene copolymer (PP-PE, 23%) was proportionally dominant among the 15 types. No significant relationship was found between the total number of observed MPs and the GIT weight. This study will help us to understand MP pollution in S. seenghala that may transmit to the human body through the food chain. [ABSTRACT FROM AUTHOR]

Results of a two-dimensional gas chromatograph time of flight mass spectroscopy (GCXGC-TOFMS) determination of polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDF) in sediments and catfish samples collected from the Msimbazi River are presented here. Samples were extracted using USEPA Method 1613. PCDD/Fs congeners in sediments ranged from 2.0 to 393.0 and 0.7 to 654.8 pg/g in the dry and wet seasons, respectively. 1,2,3,4,7,8,9-HepCDF was detected at the highest concentration, but all were lower than the USA action level of 1000 pg/g. Toxicity for each of the sampling points ranged from 19.7 to 36.5, with a mean concentration of 27.0 pg WHO 2005-TEQ g−1 in the dry season and 2.0 to 38.7 with a mean concentration of 20.7 pg WHO 2005-TEQ g−1 in the wet season. Analysis of variance (ANOVA) showed that there was no significant difference between PCDD/Fs TEQ during the dry and wet seasons (p = 0.08; α = 0.05). The highest TEQ value was estimated at Jangwani in the wet season. Toxicity of PCDD/Fs in catfish collected from the Msimbazi River ranged from 9.3 to 145.2, with a mean of 61.2 pg WHO2005-TEQg−1. Tetrachlorodibenzo dioxin (2, 3, 7, and 8-TCDD) was detected in all fish samples and ranged from 3.5 to 12.7 with a mean of 8.1 pg/g. The concentration of TCDD in fish exceeded the Agency for Toxic Substance and Diseases Registry MRL, thus posing a probable high risk to people whose dietary requirements depend on fish from the Msimbazi River. [ABSTRACT FROM AUTHOR]

Background: The genus Hypophthalmus comprises six species (H. edentatus, H. marginatus, H. fimbriatus, and H. oremaculatus), and the recently described: H. donascimientoi and H. celiae. The popular name for Hypophthalmus spp. in Brazil is mapará, this name refers to the six species. This group of fish has commercial importance for the states of Amazonas and Pará and, for this reason, requires studies to identify fish stocks. One approach is to use molecular markers, which have been very useful in studies with identification and population analysis of fish. Microsatellite molecular markers (SSRs) are one of the most informative markers for this purpose. There is little populations study of Hypophthalmus using SSRs, and there are less than six loci for the species Hypophthalmus marginatus available in the literature. With the construction of a genomic library of H. donascimientoi, we aimed to isolate and characterize SSRS markers and evaluate the extent of interspecific amplification. Methods and results: A genomic library was constructed with regions enriched of microsatellite for Hypophthalmus donascimientoi. A total of 126 contigs with 42 SSRs were used to design flanking primers for 39 microsatellites. Fifteen loci were characterized in three locations of the Solimões/Amazonas Rivers. The number of alleles ranged from one to 17 with a total of 126 alleles. The mean observed heterozygosity (HO) and expected heterozygosity (HE) were 0.721–0.692, respectively (S.d. HO 0.061 and HE 0.060). Two loci showed significant deviation in the HWE. The PIC ranged from 0.375 to 0.908. Such identified, 12 highly informative loci, and two moderately informative loci. Among the fifteen loci characterized, seven were successfully amplified in four other species of the genus. Conclusions: The microsatellite showed promise for estimating the genetic variability of H. donascimientoi and can be used as an efficient tool in population analyses of this species and in congeneric species analyzed. [ABSTRACT FROM AUTHOR]

Tachysurus latifrontalis, a new catfish species, is here described based on specimens collected from the Jiulongjiang River: a coastal river flowing into the South China Sea in Zhangzhou City, Fujian Province, South China. It belongs to the Tachysurus nitidus species group within the genus Tachysurus, defined by having a smooth anterior margin of the pectoral-fin spine, short maxillary barbels not extending to the base of the pectoral-fin spine, at least 20 anal-fin rays and a deeply forked caudal fin. This new species is distinct from the other two members of this group, Tachysurus nitidus (nec Sauvage and Dabry de Thiersant 1874) and Tachysurus fui (Miao 1934), in having a wider interorbital space [width 46.3–55.0% of head length (HL) vs. 34.3–45.5%], shorter nasal barbels (length 10.6–17.2% of HL vs. 18.1–29.2%), and a deeper body [depth at anus 17.4–27.6% of standard length (SL) vs. 13.4–22.5%]. It further differs from T. fui in having fewer anal-fin rays (20–23 vs. 27–33), a shorter (vs. longer) anal-fin base (length 22.1–28.2% of SL vs. 29.8–36.0%) and a gas bladder with (vs. without) beaded lateral and posterior margins, and from T. nitidus in having a shorter (vs. longer) (length 18.8–20.2% of HL vs. 30.8–37.4%) as well as blunt and rounded (vs. projected and slightly pointed) snout. [ABSTRACT FROM AUTHOR]

Objectives: The increase in pharmaceutical drug consumption and the presence of these drugs in the environment causes concern about their effects. Due to the prevalence of metformin in surface and waste waters, this study investigated its 7 day chronic toxicity. Typically, metformin is prescribed with other medications to control blood sugar levels and achieve healthy HbA1c (hemoglobin) levels for people with type 2 diabetes (T2D). Methods: Accordingly, the effect of metformin on catfish (Clarias gariepinus) following exposure and post-exposure recovery was evaluated using blood indices as biomarkers for hematotoxicity, electrolytes imbalance, oxidative stress, and immunosuppression. The first group was a control group, the second group was exposed to 10 mg/L of metformin, and the third group was exposed to 50 mg/L of metformin for 7 days, followed by a 15-day recovery period. Hemotoxic effects of the metformin residue on fish were reported. Results: A significant decrease in the most of antioxidants and electrolytes concentrations was observed in the present study. Low- and high- dose metformin suppressed the immunity of the exposed treated fish could be through the activation of lymphocytes and monocytes compared to control fish. Also, high dose of metformin induces cell oxidative stress through the reduction of super oxide dismutase (SOD) antioxidant enzyme and total antioxidant capacity (TAC). In addition, metformin increased the expression of inflammatory mediators as interleukin-6 (IL-6) and interleukin-1 beta (IL-1 β). However, some parameters were returned to their normal levels after 15 days post- exposure such as urea, uric acid, superoxide dismutase, chloride and IL-1 β especially with high- dose metformin exposure. Conclusion: We conclude that our findings contribute to the current eco-toxicological knowledge regarding commonly consumed drugs and have provided additional data for research into these drugs. [ABSTRACT FROM AUTHOR]

Among Siluriformes, fishes of the family Doradidae harbor dactylogyrids from Cosmetocleithrum Kritsky, Thatcher and Boeger, 1986. Anadoras grypus (Cope) (Siluriformes, Doradidae) locally named in Peru as "rego-rego" hosts a new species of Cosmetocleithrum described herein as Cosmetocleithrum infinitumsp. n. The male copulatory organ (MCO) and vagina of the new species reveal its morphological uniqueness among members of Cosmetocleithrum. The MCO in the new species is an elongate, sclerotized sinuous tube, with 12 expanded coils, with counterclockwise orientation; the accessory piece is sclerotized, comprising a kind of cone, with a large opening at its base, with a branch in the posterior middle part and with pointed ends. The vagina is a sclerotized long, winding, coiled tube with a cone-shaped opening. [ABSTRACT FROM AUTHOR]

Photo-thermal regulation of reproduction in seasonally breeding vertebrates, including teleost fishes, is established. The photo-thermal cues are relayed to the higher brain centers, where from command, neurosecretions are released to the hypothalamus to activate the hypothalamo-pituitary–gonadal axis to secrete GnRH-FSH/LH-sex steroids in general. GnRH being a pivotal regulator of reproduction, plenty of studies have been carried out to investigate the regulators of GnRH secretion. Kiss is the recently established upstream regulator of GnRH. However, studies on the regulation of kiss are highly ambiguous in vertebrates, including fishes. Therefore, attempts were made to examine the role of photoperiod and temperature in the regulation of kiss1 expression in the gonad during the late-quiescence phase of the reproductive cycle of the catfish, Clarias batrachus, employing the techniques like histology, immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA) along with analysis of data through analysis of variance (ANOVA) followed by a post hoc test and Duncan's multiple range test at P < 0.05 for comparisons amongst different groups. The study reveals that long photoperiod and high temperature stimulate the expression of kiss1 significantly (P < 0.05), while short photoperiod and low temperature suppress its expression in fish gonads (P < 0.05). Photoperiod and temperature were almost equally effective in regulating the kiss1 expression, but when long photoperiod and temperature are given in combination, their stimulatory role in kiss1 expression is amplified significantly (P < 0.05). The long photoperiod and high temperature also increase the steroid levels in gonads (P < 0.05) and stimulate gametogenesis. [ABSTRACT FROM AUTHOR]

The aim of this research was to study the influences of cold shock on some biochemical and physiological changes in Pangasius sanitwongsei. To simulate a stressor, four different water temperature levels (25 °C, 25–22 °C, 25–17 °C, and 25–15 °C) were used. Results showed that cold shock affected biochemical and physiological indices. The highest levels of ALT and glucose were found in the group subjected to 25–17 °C; meanwhile, the lowest AST was observed in a group exposed to 25–22 °C. The highest cortisol level was observed in the group exposed to 25–15 °C. The highest and the lowest levels of Na+ were found in the group exposed to 25–15 °C and 25–17 °C, respectively. The lowest level of K+ was found in the group exposed to 25–15 °C. Cl− was shown to be at its highest level in the group exposed to 25–22 °C and to have rapidly decreased in the group exposed to 25–17 °C. The highest Na+/K+ ratio was found in the group exposed to 25–15 °C and in the control group. Moreover, the Na+/Cl− ratio trend was similar to that of the Na+/K+ ratio. Furthermore, the (Na+ + K+)/Cl− ratio dramatically decreased in the group exposed to 25 to 22 °C and then slightly increased with the decreasing water temperature. Based on our results, a rapid decrease of about 8–10 °C (3 °C/h) from the ambient temperature significantly influenced stress responses, and this causes changes to cortisol, serum biochemistry, and electrolyte levels. [ABSTRACT FROM AUTHOR]

Fish have a very important place in biological monitoring studies due to the fact that they are periodic reflectors of environmental changes. In this study, we evaluated the effects of seasonality on the growth indices and antioxidant enzymes of the catfish Clarias gariepinus (Burchell, 1822) living in Aslantaş reservoir located within the borders of Karatepe National Park in Çukurova Delta. For this purpose, the morphological characteristics of 118 C. gariepinus specimens were investigated seasonally. The total length-weight relationship (LWR), Fulton's condition factor (K), hepatosomatic index (HSI), and gonadosomatic index (GSI) of fish were utilized in this study. Total protein and enzymatic antioxidant [superoxide dismutase (SOD), catalase (CAT)] activities in muscle, liver and gill tissues were determined seasonally by spectrophotometric methods. The minimum-maximum length and weight of the fish during the year were found to be 18.00–85.00 cm and 160.700–900.90 g in the winter–summer seasons. Growth characteristics of fish showed positive allometry in the spring and the summer (b = 3.69, b = 3.12), while negative allometry was found in the winter and fall seasons (b = 2.49, b = 2.51). The highest decrease in the changes of K and GSI values were found in the summer season (22.57%, 47.21%; p < 0.05), while a relative increase in the change of HSI was observed in this season (13.24%, p > 0.05). The highest decrease in total protein of muscle and liver tissues were determined in the summer season, whereas the same situation was observed for SOD and CAT activities in the winter (p < 0.05). The fish somatic indices, total length-weight relationship parameters and biochemical results will provide data in deciding whether the development of fish is at appropriate values, which will lead to effective use of the data for various works such as sustainable fish stock studies. [ABSTRACT FROM AUTHOR]

Variations of strontium isotope ratios (87Sr/86Sr) in river systems are increasingly utilised to geochemically trace origin and movement patterns of migratory fish species. Accretionary calcified structures, such as otoliths, preserve 87Sr/86Sr signatures of the surrounding water during a fish's lifetime. In this study, we present 87Sr/86Sr measurements of water samples and catfish otoliths collected in the estuaries of the Sine-Saloum (Senegal), the Gambia River (The Gambia), and the Volta River (Ghana) to assess their systematics and relationships with salinity. The three rivers possess distinct hydrological properties resulting in variable degrees of correlations between 87Sr/86Sr and salinity. The Gambia River (87Sr/86Sr of ~ 0.71209) proved exceptionally preconditioned for the approach due to well-defined geochemical end-members, allowing for quantitative estimates of salinity based on otolith 87Sr/86Sr measurements. The Volta River (~ 0.71392) presents a more complex case due the possible influence of multiple water sources to the main channel, while the inverse salinity gradient and excessive evaporation in the Sine-Saloum estuary (~0.70915) impede any significant correlations between 87Sr/86Sr and salinity. Bulk otolith 87Sr/86Sr values in the Gambia River and Volta River clearly depicted a mixed influence of seawater and riverine compositions, strongly encouraging the application of this approach for geochemical fingerprinting of critical NW African species. [ABSTRACT FROM AUTHOR]

African catfish is a freshwater species with a high ability to resist brackish water conditions, but heat stress may impair the health status of fish. Thus, the impact of varying levels of water salinity (0, 4, 8, and 12 ppt) was investigated on the growth performance, survival rate, and blood biochemistry of African catfish (average weight: 180.58 ± 2.8 g and average length: 38 ± 1.2 cm) for 4 weeks; then, fish were stressed with high temperature (32 °C) for 72 h. The growth performance and survival rate were markedly higher in fish reared in 0, 4, and 8 ppt than fish in 12 ppt (p < 0.05). Before heat stress, the superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) activities, and malondialdehyde (MDA) levels were markedly increased in fish stressed with 12-ppt salinity (p < 0.05). After heat stress, all groups showed a marked increased SOD, CAT, GSH, and MDA levels than fish before heat stress in the same manner (p < 0.05). Furthermore, fish in the 12 ppt group showed severe intestinal, gill, and liver histological features. The levels of blood glucose and cortisol were markedly increased in fish exposed with 8 and 12 ppt than 0 ppt gradually either before or after heat stress (p < 0.05). The highest values of ALT, AST, urea, creatinine, and the lowest total protein, albumin, and globulin were observed in fish reared in 12 ppt. Significant salinity and heat stress interactions were seen on the ALT, AST, urea, creatinine, total protein, albumin, and globulin values (p < 0.05). The integrated multi-biomarker response (IBR) results showed marked differences among the groups and increased gradually before and after heat stress, with the highest IBR in 12 ppt. In conclusion, growing African catfish in high salinity (12 ppt) hampered the growth performance and health status while the heat stress improved the antioxidative status vis-a-vis increased lipid peroxidation along with higher stress-related markers in expressed both blood and tissue. [ABSTRACT FROM AUTHOR]

Anthropogenic activities influence the natural equilibrium of freshwater ecosystems resulting in negative ecological impacts. Differences in the infection variables of Lamproglena clariae in relation to variable water quality influenced by metal pollution were studied at six sites along the Vaal River, South Africa (March 2017 and October 2018). From each sampling site, in situ water quality parameters, water and sediment samples, and a minimum of 10 Clarias gariepinus were collected. Lamproglena clariae specimens collected from the gills of C. gariepinus were used to calculate the prevalence, mean intensity, and mean abundance of the parasite. Metal concentrations in water and sediment were analysed with inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry. Parasite intensity correlated negatively with some water quality parameters (conductivity, salinity, pH, total dissolved solids, and dissolved oxygen). Negative correlations were found between L. clariae (intensity and prevalence) and metal concentrations (Cu, Cr, Zn, Cd) in water. Parasite infections were influenced negatively at sites with high metal concentrations recorded in sediment and water and high levels of organic pollution. Sites that were found to be more polluted had lower mean intensity and mean abundance of L. clariae, indicating pollution affects the survival of this ectoparasite. [ABSTRACT FROM AUTHOR]

Catfish which is an important component of global freshwater aquaculture production is also prone to a wide range of diseases resulting in economic losses. Improvement of the immune status of catfish is a promising preventive approach to control disease. The purpose of this study was to determine the effect of fermented earthworms as a feed additive on the non-specific immune response of walking catfish (Clarias gariepinus). Earthworms were fermented by inoculation with a bacterial mixture of Bacillus spp. and Lactococcus raffinolactis. The study featured a completely randomized design, with five treatments in quadruplicate. The various treatments consisted of fermented earthworms supplemented (FE) at at 0%, 2.5%, 5%, 7.5%, and 10% (w/w). Catfish with an average weight of 15 g were stocked at a density of 50 fish per 50 L/tank, reared for 2 months, and fed thrice a day at a feeding rate of 3% of total boby weight. The parameters observed included phagocytic activity (PA), phagocytic index (PI), extracellular respiratory burst, leucocyte differentiation, super oxide dismutase (SOD), natural agglutination, leucocrit, and hematocrit. Results showed that that FE supplemented at 2.5% significantly increased the respiratory burst activity, hematocrit, PA, PI, SOD, and leucocyte differentiation (P < 0.05) but did not affect natural agglutination. The results collectively suggest that FE as a feed additive is an effective and applicable strategy to improve the non-specific immunity of catfish. [ABSTRACT FROM AUTHOR]

Ginseng (Ge) is one of the most famous and precious consumed herbal medicines around the world. Ge plant roots have many advantages regarded as important in increasing fish production. Thus, the present study was conducted to investigate the possibility of using different levels (0.0, 100, and 200 mg/kg diet) of Ge as a reproductive enhancer agent for African catfish, Clarias gariepinus males. Results revealed that fish fed 200 mg Ge/kg diet significantly (P ˂ 0.05) increased growth performance, feed efficiency, gonado-somatic index, hematological parameters, serum follicle-stimulating hormone, total antioxidant capacity, sperm quality parameters, and ultrastructure of spermatozoa, as well as led to positively improved of the histological structure of the testes tissue compared to other treatments. Based on the obtained findings, it could be concluded that the effective use of dietary Ge at a level of 200 mg/kg as a promising reproductive agent for adult African catfish males consequently led to the sustainability of aquaculture for African catfish. [ABSTRACT FROM AUTHOR]

This work evaluated the extraction, refinement, characterization and economic analysis for producing oil rich in ɷ-3 from catfish processing wastes. All the unit operations of the extraction and refining processes were presented and the oil characterization were performed. The fatty acid profile of refined catfish oil presented, on average, fractions of 32%, 34% and 28% of the total saturated, monounsaturated and polyunsaturated fatty acids, respectively. Regards economical aspects, the estimated net present value was positive and indicated economic feasibility for all three processing waste capacity (20, 40 and 60 tons/year). The plant with the highest capacity recorded the best profitability. In this case, the net present value of US$ 764,934.62, the internal rate of return of 102.5% the earnings before interest and taxes of US$ 309,936.83/year, the return on sales of 53.18% and the profit after tax of US$ 263,446.31/year showed that the production of oil using catfish wastes is economically attractive. The minimum length of time necessary to recover the capital investment ranged from 1.56 to 2.76 years. Sensitivity analysis showed that the net present value of cash flow after tax remains positive until the price of oil reaches a threshold value of US$ 108.80/kg (20 tons/year), US$ 96.94/kg (40 tons/year) and US$ 79.65/kg (60 tons/year). [ABSTRACT FROM AUTHOR]

A Gram-positive, nitrogen-fixing and endospore-forming strain, designated P121T, was isolated from the gut of the armored catfish (Parotocinclus maculicauda) and identified as a member of the genus Paenibacillus based on the sequences of the 16S rRNA encoding gene, rpoB, gyrB and nifH genes and phenotypic analyses. The most closely related species to strain P121T were Paenibacillus rhizoplanae DSM 103993T, Paenibacillus silagei DSM 101953T and Paenibacillus borealis DSM 13188T, with similarity values of 98.9, 98.3 and 97.6%, respectively, based on 16S rRNA gene sequences. Genome sequencing revealed a genome size of 7,513,698 bp, DNA G + C content of 53.9 mol% and the presence of the structural nitrogenase encoding genes (nifK, nifD and nifH) and of other nif genes necessary for nitrogen fixation. Digital DNA-DNA hybridization (dDDH) experiments and average nucleotide identity (ANI) analyses between strain P121T and the type strains of the closest species demonstrated that the highest values were below the thresholds of 70% dDDH (42.3% with P. borealis) and 95% ANI (84.28% with P. silagei) for bacterial species delineation, indicating that strain P121T represents a distinct species. Its major cellular fatty acid was anteiso-C15:0 (42.4%), and the major isoprenoid quinone was MK-7. Based on physiological, genomic, biochemical and chemotaxonomic characteristics, we propose that strain P121T represents a novel species for which the name Paenibacillus piscarius sp. nov. is proposed (type strain = DSM 25072 = LFB-Fiocruz 1636). [ABSTRACT FROM AUTHOR]

Antimicrobial additives in personal care products (PCPs) such as triclosan (TCS) and triclocarban (TCC) are of environmental concern due to their potential toxicity in non-target aquatic organisms. In this study, the histological, genotoxic (micronucleus assay), and embryotoxic effects of sublethal and environmentally relevant concentrations of TCS and TCC were evaluated in Clarias gariepinus (the African sharptooth catfish) over a period of 28 days. The 96 hLC50 values of TCS and TCC against fingerlings of C. gariepinus were 16.04 mg/L and 41.57 mg/L respectively. The 24 hLC50 and 26 hEC50 (non-hatching) values for C. gariepinus embryos were 16.48 mg/L and 11.08 mg/L for TCS and 46.08 mg/L and 41.93 mg/L for TCC respectively. TCS was ×3 to ×4 more toxic to C. gariepinus fingerlings and embryos than TCC. Gill histological alterations ranged from mild to severe lamellar necrosis in the exposed fishes with Gill Alteration Index (GAI) of 1.60 on day 14 and 3.20 on day 28. There were significant dose-dependent increases (p < 0.05) in micronuclei and binucleated cells in the erythrocytes of exposed fishes compared to control. Embryotoxic effects assessed from 0 to 72 h post fertilization showed significant decreases (p < 0.05) in hatching success and number of heartbeats per minute, and significant increase (p < 0.05) in percentage abnormalities in the exposed embryos compared to control. The study demonstrates the need for regulatory measures and monitoring of the use of TCS and TCC in PCPs in order to mitigate potential adverse effects to non-target aquatic organisms. This will support the United Nations Sustainable Development Goal 14 on sustaining life below water. [ABSTRACT FROM AUTHOR]

The restricted range, taxonomic uncertainties and the apparent phylopatric behavior of Parotocinclus (dwarf plecos) make this fish group an excellent model to infer diversification patterns in Neotropical rivers. Thus, the aim of this study was to investigate the spatial–temporal relationships and the presence of cryptic forms in Parotocinclus cristatus from poorly known and human-impacted drainages in northeastern Brazil based on mitochondrial COI (589 bp) and Cyt-b (835 bp) and nuclear (Rhodopsin, 473 bp) markers. The phylogenetic reconstruction, haplotype network and species delimitation algorithms revealed three conspicuous and restricted molecular operational units (MOTUs) within P. cristatus. The samples from Cachoeira and Una basins represent a single MOTU dating back to the Early Pliocene, resulting in deep genetic divergence when compared to the other lineages. The MOTUs from Contas and Almada river basins diverged around 2.1 Ma, while the latter encompassed highly structured populations between upper and lower watersheds (0.6 Ma, Pleistocene). The closest relationship between more distant basins than nearby drainages indicates an intricate scenario of headwater captures that challenge traditional studies based on current geographic reliefs and ichthyofauna inventories. Therefore, caution when biogeographic inferences are carried out without further understanding about the genetic diversity and the geomorphological history, as commonly reported in fishes from eastern basins in Brazil. Finally, the conspicuous Linnean and Wallacean shortfalls in dwarf plecos, including unique lineages from unprotected and highly degraded areas, justifies a thorough review of their taxonomic status since valid species are the major source of information for defining conservation policies. [ABSTRACT FROM AUTHOR]

Numerous active pharmaceutical ingredients (APIs) have been detected in various environmental matrices. Thus, their potential to elicit their toxic effect on non-target organisms is a growing concern, especially in the aquatic environment. This study aimed to investigate the potential toxicity of ibuprofen (IBU) at environmentally relevant concentration on the haematology and histology of the gill, liver, and kidney over 30 days. The 96-h acute toxicity data showed that IBU was moderately toxic to C. gariepinus with an LC50 value of 3.78 mg/L. After 15 and 30 days of exposure, there was a significant alteration in haematological indices in the treated fishes when compared to the control group. Throughout the experimental duration, the level of the mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) were consistently lower significantly, in contrast to the control group. IBU induced histopathological deformities in the gills, liver, and kidney of the exposed fishes, with alterations such as showing severe secondary lamella necrosis (SLN), epithelial lifting (EL), mild deformity of the secondary lamella (DSL), mild secondary lamella necrosis (MLN), and mild vascular congestion in the liver and kidney, respectively. This study has demonstrated that IBU at environmentally relevant concentrations can significantly impact the haematology, gills, liver, and kidney of C. gariepinus. This study's results can provide baseline info for regulatory agencies to set safe limits for NSAIDs as a safeguard for the aquatic environment. [ABSTRACT FROM AUTHOR]

Acute toxicity (96 h LC50) of phenol was analyzed in the cat fish Mystus vittatus in static bio-assay over a 96-h exposure period using probit method. The 24, 48, 72, and 96 h LC50 values (with 95% confidence limits) of phenol for fingerling catfish were found out as 13.98, 13.17, 12.62, and 12.21 mg/l respectively. Investigations pertaining to the histopathological sections have shown high degree of pathological lesions observed in various parts like gill, liver intestine, and kidney of the fish species. Analysis of gill section revealed observable changes in the experimental species such as fusion, malformation at the tip of secondary lamellae, vacuolation, hyperplasia, and epithelial damage. Exposure of phenol showed cytoplasmic vacuolation, tissue damage, and loss of hepatic cell wall in the liver of experimental organism. Lesions of tissue damage at the epithelial site, inflammation, and clumping of adjacent villi made of columnar epithelium have been observed in the intestine of fish, and also the excretory part of the fish kidney revealed various changes like glomerular atrophy, damage of Bowman's capsule, vacuolization, and degeneration of renal epithelium. The current study on histological changes observed in the experimental organisms has thrown light on the current scenario which poses threat and danger to the whole aquatic ecosystem, and this study plays a vital role in assessing the aquatic pollution. [ABSTRACT FROM AUTHOR]

The trace elements concentration in the fish estimates the contamination degree in the aquatic environment. These toxic trace elements are transported into the human through the consumption of polluted fish. This study estimated the effect of Cd, Hg, Pb, As, and Al on tilapia species and catfish Clarias gariepinus (six for each species of fish) inhabiting Burullus Lake—Egypt 30° 33′–31° 08′ E and 30° 22′–31° 35′ N. The highest Pb concentrations recorded in the muscle of C. gariepinus 2.29 ± 0.29 μg/g while S. galilaeus was estimated the lowest Hg concentration of 0.54 ± 0.02 μg/g which indicated the presence of contaminants exceeded the limits permitted by FAO/WHO and EC. The maximum mean carbohydrate, lipid, and protein recorded in O. niloticus 18.66, 16.33, and 58.16 mg/g, respectively; moisture in O. aureus 67.33%; and ash 16.41% in O. niloticus. The lowest amount of carbohydrate was recorded in the T. zillii 14.1 mg/g, lipid, and ash in C. gariepinus 11.65 mg/g and 3.375%, respectively. Protein and moisture in the S. galilaeus were 53.75 mg/g and 60.75%, respectively. The results recorded a marked insignificant (P > 0.05) decrease in CAT, GR, and GPx activity in O. niloticus. GSH and SOD activity was an insignificant (P > 0.05) decrease in C. gariepinus. The results concluded that the trace elements concentrations exceed the maximum permissible limits recommended in fish samples set by Egypt, FAO, WHO, and EC. The estimated weekly intake of all elements through consumption of studied fish species inhabiting Burullus Lake by a child (15 kg) in Egypt is well above the PTWI recommended by FAO/WHO, whereas it is well below the PTWI for human consumption by young people (40 kg) and adult person (70 kg), at least in respect of residual levels of studied elements excluding Cd and Hg. Thus, for consumer protection, these fish species are unsafe and have hazardous effects for children, and about youth and adult consumption, caution must be taken to consider individuals eating significant amounts of fish. [ABSTRACT FROM AUTHOR]

In seasonally breeding vertebrates, extrinsic factors like photoperiod and temperature are major determinants, controlling the annual reproductive cycle. In teleosts, kisspeptin, which occurs in two molecular forms: kisspeptin1 (Kiss1) and kisspetin2 (Kiss2), has been reported to alter gonadotropin (Lh and Fsh) secretion but its effect on gonadotropin-releasing hormone (Gnrh) secretion is not unequivocally proved. In the catfish Heteropneustes fossilis, we isolated and characterized kiss2 and gnrh2 cDNAs and the present work reports effects of altered photo-thermal conditions and melatonin (MT, a pineal hormone) on their expressions in the brain. The exposure of the catfish to long photoperiod (LP, 16 h light) at normal temperature (NT) or high temperature (HT, 28 °C) at normal photoperiod (NP) for 14 or 28 days stimulated both kiss2 and gnrh2 expression in both gonad resting and preparatory phases with the combination of LP + HT eliciting maximal effects. Short photoperiod (SP, 8 h light) under NT or HT altered the gene expression according to the reproductive phase and temperature. MT that mediates photo-thermal signals to the brain inhibited brain kiss2 and gnrh2 gene expression in the NP + HT, LP + NT, and SP + NT groups. The altered photo-thermal conditions elicited changes in steroidogenic pathway as evident from changes in plasma E2, progesterone, and testosterone levels. The results show that brain kiss2-gnrh2 signaling is involved in photo-thermal-mediated mechanisms controlling reproduction. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the in vitro and in vivo efficacy of propolis against Ligictaluridus floridanus on Ictalurus punctatus gills. Methods: This study used an ethanol extract of propolis at a concentration of 300 mg mL−1, with a total polyphenol concentration of 2.77 mg mL−1 as determined by chromatography. In vitro trial used propolis concentrations at 5, 30 as well as 60 mg L–1 and a 70% ethanol control group to treat naturally infected catfish. The in vivo experiment was 16 weeks in duration, consisting of seventy-two fish infected by cohabitation and subjected to one-hour baths every 72 h during the trial. Results: In vitro studies showed that parasites exposed to 60 mg L−1 of propolis displayed a significant reduction (p < 0.05) in their survival time. In vivo studies confirmed the reduction of intensity and abundance of Ligictaluridus floridanus on the gills of channel catfish. Conclusion: This study has provided the first challenge of propolis against L. floridanus on I. punctatus gills and shows that propolis has an anthelmintic effect. [ABSTRACT FROM AUTHOR]

Enzymatic biomarkers, especially oxidative-stress enzymes, are useful for assessing the status of aquatic environments. The present study used biochemical markers determined in nervous, gill, and liver tissues of Sciades herzbergii, concomitantly with analyses of trace metals in the tissues and bottom sediment, to evaluate environmental quality in Amazon estuaries. The study was conducted from March 2014 to February 2016 in two areas: Caeté estuary in Bragança, state of Pará, which is relatively unimpacted; and São Marcos Bay, next to a harbor in São Luís, state of Maranhão. In the laboratory, the fish were weighed (g) and measured (cm). Fragments of the gills, the brain, and the liver were biochemically analyzed, and the metal contents in the brain, the liver, and the muscle tissues were determined. Turbidity was significantly higher (p < 0.05) in São Marcos than in Bragança. Specimens of S. herzbergii were smaller in São Marcos, and aluminum, iron, nickel, copper, cadmium, and mercury levels were higher in bottom sediment (p < 0.05) collected at this location. Fish from São Marcos contained significantly higher (p < 0.05) concentrations of aluminum, iron, and cadmium in the muscle tissue than fish from Bragança. In addition, fish from São Marcos had significantly higher concentrations of nickel in both the nervous and hepatic tissues. Only fish from São Marcos contained measurable concentrations of mercury in the liver and muscle. Fish from Bragança had copper concentrations in the liver significantly different from those captured at São Marcos (p < 0.05). The activities of gill glutathione S-transferases (GSTs) (F = 6.62; df = 1, 16; p < 0.05) and liver CAT (F = 10.22; df = 1, 16; p < 0.05) were higher in fish from São Marcos. However, ChE in brain tissues and lipid peroxidation (LPO) in the gills and liver did not differ significantly between fish from both areas. The physico-chemical conditions of the water and the concentrations of metals found in sediment and biological tissues, together with the biochemical responses of S. herzbergii in the study areas, indicate that this species is still tolerant to adverse environmental conditions, but the presence of metals is a risk to the health of fish, mainly to fish from São Marcos, especially if chronically exposed. [ABSTRACT FROM AUTHOR]

Diplostomum ardeae Dubois, 1969 has seldom been reported since its description from the great blue heron (Ardea herodias L., 1758) in the USA. Sequences obtained in this study from the barcode region of cytochrome c oxidase 1 (CO1) in diplostomids from black-crowned night heron (Nycticorax nycticorax (L., 1758)) in Puerto Rico matched data from D. ardeae from A. herodias in the type region. We also obtained DNA barcodes from morphologically similar diplostomids from a rufescent tiger heron (Tigrisoma lineatum (Boddaert, 1783)) and from metacercariae from eye lenses of Trachelyopterus galeatus (Linnaeus, 1766) from the Paraná River basin in Argentina and Brazil, respectively. Barcodes matched (97–100% identity) in these South American adult and larval specimens as well as in recently published sequences from metacercariae from 11 other siluriform fishes from the same region. Barcodes from the South American species, which we describe as Diplostomum lunaschiae n. sp., differed from those of D. ardeae by 7.2–9.8%, and the new species differs from D. ardeae in its size, pharynx:oral sucker length ratio, egg:body length ratio, and distribution of vitellaria. As in prior phylogenetic analysis of CO1 sequences, both D. ardeae and D. lunaschiae n. sp. were not associated with Diplostomum. In more character-rich analyses of nuclear rDNA and of mitochondrial genomes, D. ardeae was an early divergent member of clades of species of Diplostomum. Consequently, we continue to consider D. ardeae and D. lunaschiae n. sp. members of Diplostomum, in contrast to recent suggestions that these species may belong to a different genus. [ABSTRACT FROM AUTHOR]

Growth performance and apparent digestibility coefficient (ADC) of fatty acids, amino acids and macronutrients for diet containing fish meal, Chlorella vulgaris or Spirulina platensis (=Arthrospira platensis) by African catfish (Clarias gariepinus) were assessed in a 42-day feeding trial using a fishmeal-based control diet (REF) and two other test diets containing Spirulina or Chlorella replacing fishmeal in the control diet. The Spirulina-based diet exhibited higher ADC of crude protein than the Chlorella-based diet. The Spirulina- and Chlorella-based diets exhibited higher ADC for all essential amino acids (EAA) when compared with the control diet. High methionine and lysine ADC of Spirulina and Chlorella diet were also observed. The Chlorella diet was significantly higher in ADC of histidine, arginine, valine, isoleucine and tryptophan. Chlorella diet had the highest ADC values for n_6 and n_3 PUFA, lipid. The Spirulina diet exhibited significantly higher lysine, crude fibre, energy, dry matter carbohydrate and docosahexaenoic acid (DHA)ADCs than the Chlorella diet. EPA of reference diet was however, significantly more digestible than Chlorella but not in Spirulina. [ABSTRACT FROM AUTHOR]

An analytical protocol for the determination of multi-class pesticide metabolites chlorpyrifos-methyl (Chlorp-M), S-metolachlor (S-Metola), malaoxon (malaox), 2-chloro-4,6-diamino-1,3,5-triazine (2-CAAT), carbofuran phenol (CarbPhenol), 3-phenoxybenzoic acid (3-PBA) and one polycyclic aromatic hydrocarbon metabolite 1-hydroxypyrene (1-OHP) in fish was developed using the analytical technique GC–MS. Besides the verification of metabolite occurrence in catfish from both metropolitan region and intensive farming region, the protocol was applied to evaluate human health risk due to the contaminated fish consumption in Brazilian tropical semiarid coast, for the first time. Following the national and international quality standards, the analytical protocol showed acceptable recoveries with good repeatability. Limit of detection (LD) and limit of quantification (LQ) values ranged from 0.15 µg L−1 to 36.0 µg L−1 and from 0.55 µg L−1 to 112.9 µg L−1, respectively, and the sensitivity was considered satisfactory since it is a complex matrix. Only tree pesticide metabolites were detected in the captured catfish. CarbPhenol and 3-PBA presence may be attributed to the application in rural and urban activities for pest control, public health campaigns and household, while malaox presence may be due to the dengue control program. Malaox contents were significantly higher than 3-PBA and CarbPhenol for the three estuaries of the Ceará coast, but the dietary risk due to the consumption of these fish, mainly for the coastal communities, based on the values established for their parental compounds, was considered low for both 3-PBA and malaox, and of probable high risk for CarbPhenol. Results represent an alert to the high possibility of risks to human health due to the overuse of pesticides in Brazil, mainly carbofuran pesticide. [ABSTRACT FROM AUTHOR]

In the Afrotropic region, the genus Clinostomum is represented by four accepted and four unnamed species distinguished using molecular data. Here, we describe one of the four unnamed species as Clinostomum ukolii n. sp. based on metacercariae from siluriform fishes (Synodontis batensoda, Schilbe intermedius) collected in Nigeria and South Africa. The new species is distinguished by molecular data (39 new sequences of partial cytochrome c oxidase I ≥ 6.7% divergent from those of other species) and morphological differences from named and unnamed species in the same region. Metacercariae of C. ukolii n. sp. can be distinguished based on size, tegumental spines, and various aspects of the genital complex, including its position, lobation of the anterior testis, and the disposition and shape of the cirrus pouch. Although descriptions of new species of digeneans are typically based on the morphology of adults, we argue that in cases where data are available from metacercariae from regionally known species, new species can be described based on metacercariae, particularly when supported by molecular data, as here. Moreover, sub-adult reproductive structures can be clearly visualized in metacercaria of Clinostomum. Considering metacercariae as potential types for new species could advance clinostome systematics more rapidly, because metacercariae are encountered much more often than adults in avian definitive hosts. [ABSTRACT FROM AUTHOR]

The objective of the study was to verify the combination of live and frozen Artemia nauplii, in different salinized water, and its influence in growth and survival of the catfish Lophiosilurus alexandri (Steindachner, 1876) larvae. Larvae were exposed to a combination of two feeds and two different salinities: live Artemia nauplii + 0‰ salinity in the water; live Artemia nauplii + 2‰ salinity in the water; frozen Artemia nauplii + 0‰ salinity in the water; and frozen Artemia nauplii + 2‰ salinity in the water. The experiment was conducted in a randomized design, in a 2 × 2 factorial scheme, 5 replicates, during 15 days. The larvae final weight, weight gain, food conversion, standard and total length, biomass, survival, body width, intestinal quotient, Fulton's condition factor, and water quality were evaluated. The use of Artemia nauplii and 2 ppm salinized water for L. alexandri larviculture proved to be adequate providing greater growth. This was due to Artemia nauplii being kept alive and attractive for the cultivation of larvae in salinized water, even though salt was a stress factor. Already, the frozen Artemia nauplii was a viable food but should be used preferably in times of lack of live nauplii and without salinization of the water. [ABSTRACT FROM AUTHOR]