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The study assesses associations between microelement levels, fatty acid composition, and oxidative stress markers in grass carp muscle in the summer and autumn seasons. Additionally, various factors were considered, including the estimated daily intake (EDI), target hazard quotient (THQ), total THQ (TTHQ), and metal pollution index (MPI), to evaluate potential health risks for consumers. The microelements (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Ni, Pb, Se, Sr, and Zn) were determined using inductively coupled plasma optical emission spectrometry (ICP-OES), and total mercury was determined using cold-vapor atomic absorption spectroscopy (CV-AAS). Fatty acid profiling was realized using gas chromatography (GC) detection with a flame ionization detector (FID). The overall tendency of microelement levels was as follows: Fe > Zn > Al > Sr > Ba > Ni > Se > Cr> Cu > Mn > Pb > As > Li > Hg;

Introduction: Megaleporinus obtusidens , also known as "boga," is a freshwater teleost fish species widely distributed across South America with significant commercial value in Argentina and Brazil. Fishers, particularly those in the lower Paraná River, frequently classify the fish they catch as M. obtusidens. Despite various approaches, including cytogenetics, molecular data, and morphological analysis, the taxonomic classification of the boga fish remains debated among researchers, resulting in discrepancies in the literature. Methods: This study aimed to assess the diversity of specimens captured in the La Plata River Basin, initially classified as Megaleporinus obtusidens by fishers, using DNA barcoding. The mitochondrial COI marker was employed to explore species assignment and genetic diversity in Megaleporinus , a genus with high commercial exploitation in the southern area of the La Plata Basin. Results: Our findings indicate that some boga samples, previously identified as M. obtusidens , are actually M. piavussu. We also observed significant differences in the geographic distribution, diversity, and genetic structure between the two species. Discussion: These results highlight the importance of studying the ecology of each species separately. Proper resource management, based on accurate species identification, is critical for the conservation of ichthyofauna in the region. [ABSTRACT FROM AUTHOR]

PCBs were analysed in 110 samples, including marine fish, freshwater fish and marine bivalves. The levels of ∑7PCBs in marine fish ranged from 0.18 to 5.59 ng g−1 wet weight (ww), in freshwater fish from 0.10 to 1.19 ng g−1 ww and in marine bivalves from 0.07 to 5.59 ng g−1 ww. The highest level of PCBs was found in Scomberomorus niphonius. In marine fish, freshwater fish and marine bivalves, the most abundant compounds were Hexa-CBs, Tri-CBs and Hexa-CBs, respectively. PCBs were distributed in a species-specific manner in aquatic products. None of the aquatic product samples analysed exceeded the limit for ∑7PCBs set by China or the limit established by the European Union. [ABSTRACT FROM AUTHOR]

Immigration and emigration are key demographic processes of animal population dynamics. However, we have limited knowledge on how fine-scale movement varies over space and time. We developed a Bayesian integrated population model using individual mark-recapture and count data to characterize fine-scale movement of stream fish at 20-m resolution in a 740-m study area every two months for 28 months. Our study targeted small-bodied fish, for which imperfect capture was accounted for (bluehead chub Nocomis leptocephalus, creek chub Semotilus atromaculatus and mottled sculpin Cottus bairdii). Based on data from 2021 individuals across all species, we found that proportions of immigrants in 20-m sections averaged 30–42% among the study species, but they varied over space and time. Creek chub immigrants increased during warmer intervals when individuals grew more and transitioned between body size classes, suggesting that immigration was due to ontogenetic habitat shifts. There was a weak pattern across the species that individuals were more likely to leave 20-m sections when flow was higher. Water-column species (bluehead chub and creek chub) were more likely to immigrate into and stay in deeper sections with more pool area. Across all species and occasions, number of immigrants to stream sections did not decrease with number of individuals that survived and stayed in the same sections. Thus, the habitat did not appear saturated, and our data provided no evidence that intra-specific interactions affected fine-scale movement at our fish densities. In conclusion, high turnover rates characterized fish movement among stream sections and their variation was associated with temporal and spatial shifts in abiotic conditions. [ABSTRACT FROM AUTHOR]

The concentration of mercury, fatty acids and lipid quality indices were determined in three species of fish (European eel, Anguilla anguilla Linnaeus, 1758; Eurasian perch, Perca fluviatilis Linnaeus, 1758; and roach, Rutilus rutilus Linnaeus, 1758). The fish were caught from a reservoir in the Warmia and Mazury region located near Olsztyn (north-eastern Poland). Mercury content was determined by atomic absorption thermal decomposition using Milestone DMA-80 (Italy), whereas fatty acids were measured by gas chromatography using a 7890A Agilent Technologies chromatograph. The total mercury concentration had the following sequence: European perch (0.297 mg/kg) > European eel (0.160 mg/kg) ≈ roach (0.100 mg/kg) (P<0.05). A positive correlation was found between the mercury content and size (the body weight and total length) of these fish (P<0.0001). Based on the THQ, HI (<1.0) and BRQ (1.063), it was concluded that the fish does not pose a health risk and is fit for human consumption. Similarly, low AI and TI values (<1) are beneficial to human health related to reducing the risk of ischemic heart disease. A low OFA index of C12+C14+C18 and a high index of C18+UFA also indicate that these fish are safe from a nutritional point of view. The fatty acid indices HH (32.10–74.30), NVI (0.83–2.14), DI(18) (65.50–89.28), DI(16) (18.45–32.96), UI (131.93–278.64) and PI (88.60–314.90) were also studied. However, higher PUFA/SFA and de minimis EPA+DHA/Hg ratios compared to the recommended ratios suggest further research in this area is needed. [ABSTRACT FROM AUTHOR]

Diets of fish larvae may vary within populations and among species and are affected by larval prey availability and foraging capacity. We aimed to describe the diet of fish larvae based on empirical field observations, emphasizing the interaction and organization of the predator–prey network using Auchenipterus osteomystax as a species model. The network showed few interactions (low connectance and modularity) but a nested structure (some items that had fewer records tended to occur together with the most frequent ones), low complementary specialization (the proportions of ingested items tended to be equivalent) and a pattern of segregation (some items tended not to be consumed together) in the use of resources among individuals. Robustness was low when the removal of prey with a higher consumption frequency occurred. The correlation between morphological variables and network attributes was significant and positive for abundance and strength, while the correlation with nested rank was negative. The availability of suitable dietary resources is likely to be the key factor for success and survival in the early stages of development. With changes in morphology during larval development, A. osteomystax showed a generalist position in the network as its predation capacity increased. A new approach to trophic ecology studies of fish larvae incorporating network analysis may help explain the individual characteristics of larvae and assess the pattern of interactions in the population. [ABSTRACT FROM AUTHOR]

Riverine fish assemblages are strongly influenced by attributes of the flow regime. Tropical savannah river systems have distinct and predictable hydrologic seasonality, reflecting the wet‐dry climate, but can vary substantially in terms of dry season flow permanency and wet season flow‐pulse characteristics. Understanding how flow permanence and variability influence fish assemblages, and whether these factors can be used to predict responses to future hydrological change, are key knowledge gaps that impede effective management. We examined the influence of hydrological variability on the structure and diversity of freshwater fish assemblages across rivers of the wet‐dry tropics of northern Australia. We found distinct fish assemblages that varied predictably across three hydrological river types: Intermittent, Perennial Stable and Perennial Flashy flow regimes. This distinction emerged despite a common species pool across the region. Species richness was greatest in rivers with Perennial Stable flow regimes, whereas beta‐diversity was greatest in Intermittent rivers. However, life history strategies of constituent species were generally poor predictors of species abundances within each hydrological river type. The distinct fish assemblages evident among hydrological classes may provide some cautious ability to both predict potential fish assemblage changes with future hydrological changes (e.g. if perennial streams became more flashy or intermittent), and to predict fish assemblages expected in unsampled rivers with particular hydrological characteristics. Our findings provide further support for the importance of maintaining regional flow‐habitat heterogeneity and the connectivity between hydrological river types, and their essential role for conserving tropical fish species diversity into an uncertain hydrological future. [ABSTRACT FROM AUTHOR]

We conducted feeding experiments under controlled conditions and assessed the trophic transfer of radiocesium in three salmonid species (Oncorhynchus nerka, O. masou, and Salmo trutta) with different body sizes. The assimilation efficiency of 137Cs from the 137Cs-containing feed until day 252 was clearly higher in small-sized than in large-sized fish across all species. After the diet was changed from R pellets (containing 137Cs) to non-contaminated pellets, the 137Cs excretion coefficient for the excretion period (days 56–252) was clearly higher in small-sized than in large-sized fish across all species. The effective half-lives of 137Cs in the small-sized and large-sized fish of each species ranged from 34.5 to 40.3 days and from 86.2 to 100.8 days, respectively. The steady-state 137Cs concentrations for the uptake period (days 0–252), as estimated by a model, were higher in large-sized than in small-sized fish across all species. Therefore, differences in body size may partly contribute to the varying 137Cs contamination levels observed in the muscle of the fish. [ABSTRACT FROM AUTHOR]

Investigating the ontogeny of threatened freshwater fishes is vital for designing future conservation actions that will increase the potential of species' persistence. This study provides a detailed description of the early life stages of a threatened freshwater fish species, the Evrotas minnow Pelasgus laconicus, which occupies aquatic ecosystems with extreme seasonal hydrological variation. The study of the embryonic and juvenile stages was conducted in vivo using light microscopy from eggs obtained from acclimatized wild spawners at 20 ± 1°C. Fertilized eggs were spherical and transparent with a mean diameter of 1.24 ± 0.06 mm and the average length of free embryos at hatching was 3.85 mm NL (notochord length). The main morphological changes observed are related to the absorption of the yolk, the increase and distribution of the melanophores and the sequential development of the fins. In conclusion, the Evrotas minnow was identified as a multiple spawner, exhibiting a protracted reproductive period (March to August), a particularly short egg‐hatching period (5–6 days), a short free embryo stage and a rapid onset of exogenous feeding (2 days). The conservation implications of our study, such as safety stock creation, population reintroduction, conservation of fish refugia and breeding habitats and beaver dam analogues, are discussed. [ABSTRACT FROM AUTHOR]

This study presents an updated fish checklist of the Sultan Idris Shah Forestry Education Centre (SISFEC), Puchong, Selangor, Malaysia. Fish samples were collected using gill nets, cast nets, scoop nets, baited lines, and electrofishers at eight sites within SISFEC, including Rasau River, Bohol River, and several lentic water bodies. There are 29 fish species, representing 13 families of freshwater fish, with the family Danionidae (six species) dominating the list. Of the 29 species recorded, six were non-native, including Oreochromis niloticus, Barbonymus gonionotus, Puntigrus tetrazona, Pterygoplichthys disjunctivus, Oreochromis sp. (red), and Poecilia reticulata. In addition to the non-native species recorded, the Australian red claw crayfish, a non-native invasive invertebrate, was also encountered. Despite the increase in recorded native species compared to past reports, potential threats from invasive species remain a concern. Regular monitoring and strict regulation are recommended to ensure the conservation and sustainable use of SISFEC's aquatic biodiversity. [ABSTRACT FROM AUTHOR]

Invasive non-indigenous species have been reported to cause harm to ecosystems, including freshwater ecosystems, and reduce species abundance. As the world became more alert to the introduction of non-indigenous species, the demands for developing preliminary management measures have also increased. Thus, this study aimed to develop a habitat suitability assessment approach for non-indigenous freshwater fish with cost-effective data access. This approach utilized the Köppen-Geiger climate classification maps and fish occurrence data to predict the present (1980–2016) and future (2071–2100) habitat suitability of Oreochromis niloticus and Poecilia reticulata in South Korea. A fuzzy inference system was applied to relate climatic variables based on the Köppen-Geiger climate classification and species occurrence records. The results indicate that the habitat of the two species is limited to sites near sources of thermal pollution (for overwintering) in the present, and habitable area will expand in the future as the temperature increases. This approach is expected to aid non-experts in decision-making processes regarding non-indigenous freshwater fish management by evaluating potential habitats through the transfer of quantitative climate variables into linguistic or intuitive variables. Further augmentation in the climate zone classification method is expected to aid developing management strategies. Additionally, this approach is anticipated to facilitate the application of habitat prediction results by shortening the gap between experts and non-experts. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of incorporating biological silage from tambaqui (Colossoma macropomum) by-products (BST) on the performance, hematological and plasma biochemical parameters, and egg quality (physical, proximate composition and sensory characteristics) of older commercial hens. The BST was prepared by ensiling tambaqui by-products with lactic acid bacteria, cassava trimmings, and preservatives, producing a nutrient-rich, high-protein feed ingredient. One hundred and twenty Hisex Brown hens (83 weeks old) were divided into five treatment groups, each receiving diets with 0, 1, 2, 3, or 4% BST. Performance metrics, egg quality parameters, and blood samples were collected over 63 days. The results showed that diets with 1 to 2% BST improved egg weight, eggshell quality, and feed efficiency without adverse effects on hen health. However, higher BST inclusion levels led to declines in feed intake, egg production, and mineral content in eggs, possibly due to the sensory properties of the tambaqui-based diets. Hematological analysis indicated an increase in MCV and MCH values with higher BST levels, while triglycerides increased and cholesterol decreased, suggesting potential benefits for lipid metabolism at moderate inclusion levels. Sensory analysis of eggs showed greater acceptance in diets with 3% to 4% BST due to yolk color enhancement, although higher levels were not optimal for hen productivity. These findings support BST as a viable alternative feed in poultry diets, promoting waste utilization in a sustainable, circular economy model for the agribusiness sector. [ABSTRACT FROM AUTHOR]

The Neotropical region exhibits a remarkable diversity of freshwater fish, with the Upper Grande River in the La Plata basin emerging as a significant yet underexplored hotspot. However, this region is confronted with escalating threats from human activities, such as hydroelectric damming and urbanization, which jeopardize its ichthyofauna. This research conducted a comprehensive inventory of the ichthyofauna in the Upper Grande River, covering diverse environments and sub-basins. Fish sampling at 185 sites revealed over 94 species, indicating a high richness and abundance of migratory fish, as well as the presence of two endangered species. While the study provides valuable insights into fish species richness and distribution, accumulation curves suggest the need for additional sampling efforts. The presence of non-native species, especially in the Aiuruoca and Grande sub-basins, raises conservation concerns. The study underscores the Upper Grande River’s critical role as an area for fish diversity, emphasizing the necessity for ongoing monitoring, conservation efforts, and additional sampling to fully uncover the extent of its ichthyofauna. [ABSTRACT FROM AUTHOR]

Although the toxicity of selenium (Se) and carbamazepine (CBZ) has already been demonstrated, the possible effects of freshwater fish co-exposure to these pollutants have not been explored. Thus, we aimed to evaluate the potential impact of Se and CBZ (alone and combined) exposure (both 5 µg/L) in Oreochromis mossambicus after 28 days. Exposure to CBZ, alone or combined with Se, significantly increases the "red blood cells" and "mean corpuscular volume." In the gills, malondialdehyde levels in the "CBZ" and "Se + CBZ" groups were lower than in the control group. Furthermore, the exposure to treatments induced a significant increase in protein carbonyl formation in gills and DNA damage in gill and liver cells. Still, acetylcholinesterase activity in the brain was not changed. Thus, our study provides insight into the toxicity of metals and pharmaceutical drugs and warns about the ecotoxicological risk posed by such mixtures. [ABSTRACT FROM AUTHOR]

Pre-treatment processing technology plays a crucial role in the overall freshwater fish processing procedure, and automatic head and tail cutting stands out as a significant pre-treatment technique within the industry. The system for removing the head and tail of freshwater fish comprised a Cartesian coordinate manipulator, a fish transfer device, a control system, and an image acquisition device. In the vision system, five image segmentation methods were utilized for fish head and tail image segmentation comparison tests. These methods include U-Net (U-shaped Deep Neural Network), DeeplabV3, PSPNet (Pyramid Scene Parsing Network), FastSCNN (Fast Semantic Segmentation Network), and ICNet (Image Cascade Network), all of which were employed to evaluate their performance. Among the tested segmentation methods, the ICNet demonstrated the most excellent segmentation capability. The experimental results indicated a segmentation accuracy of 99.01%, a mean intersection over union (MIoU) of 82.50%, and an image processing time of 15.25 ms. The results showed that the fish head and tail were successfully cut off using this model for recognition with a circular knife. Consequently, the segmentation model employed in the machine vision system within this study has demonstrated successful applicability in automatically cutting the heads and tails of freshwater fish of various sizes. [ABSTRACT FROM AUTHOR]

A new species of Characidium shared by adjacent tributaries of the upper portions of the Tapajós and Xingu river basins is described. Characidium varii, new species, can be distinguished from the congeners by having distinctly speckled pattern of colouration, including dark blotches on cheek and ventral surface of head, by having conspicuous dark marks on fins, along with a single row of dentary teeth, isthmus completely covered by scales, 14 circumpeduncular scales, and swimbladder reduced. Molecular data reinforce the validation of the new species. The distribution of C. varii supports the hypothesis of the existence of a faunistic mixing between Tapajós and Xingu river basins, corresponding to the region of the Serra do Cachimbo and surrounding areas, previously proposed in the literature. [ABSTRACT FROM AUTHOR]

Atlantic salmon populations face a number of significant, human-driven threats such as overfishing and thermal stress from anthropogenically-accelerated climate change. A considerable body of research has been devoted to such large-scale threats as well as catch-and-release fishing, while the potential impacts of other recreational activities on Atlantic salmon while in rivers have been largely overlooked. Here, we undertook a systematic literature review of the effects that recreational activities (excluding direct impacts of catch-and-release angling) might have on the welfare and survival of Atlantic salmon in riverine systems at all relevant life history stages. Examples of relevant activities examined here include swimming, all-terrain vehicle (ATV) use, and underwater photography. We also performed a relative risk assessment of such activities based on the likelihoods of their occurrence and the severities of their potential impacts. For the most part, the impacts of non-angling recreational activities on Atlantic salmon are likely widespread but largely temporary. Redds, eggs, and juveniles were generally found to be more susceptible to most threats than smolts and adults. However, some activities have significant destructive potential such as ATV use in or around spawning habitats. Significant risks also remain concerning pathogen and invasive species transfer via angling gear, waders, canoes, and other equipment that may be moved across systems without proper cleaning. Although we focused primarily on risks to native Atlantic salmon populations in eastern Canada, the risk assessment framework developed here is broadly applicable and easily adaptable for management in other contexts and jurisdictions with populations of riverine Atlantic salmon and potentially other migratory salmonids too. [ABSTRACT FROM AUTHOR]

Background: Understanding the processes that influence distribution of organisms is a major goal in evolutionary biology. Speciation in freshwater fishes is mainly associated with the "island-like" model of evolution, in which the formation of land barriers between different hydrographic basins interrupts gene flow and promotes isolation. Freshwater fish therefore provide an excellent model system for macro- and micro-evolutionary studies. The Mesa Silverside, Chirostoma jordani, is one of the most widespread freshwater fish species in the Mexican Plateau, a geologically complex physiographic region with a long history of genesis, destruction and compartmentalization of hydrographic basins that has promoted the dispersal and isolation of freshwater fishes. Methods: We used mitochondrial (Cytb and D-loop) and nuclear (first intron of the ribosomal protein S7) data and used phylogeographic and coalescent based methods to elucidate the evolutionary history of C. jordani throughout its distributional range on the Mexican Plateau. Results: The results obtained in the present study revealed that C. jordani consists of two main genetic groups with geographical correspondence. Clade I occur exclusively in north-western basin and shows population structure. Clade II is widely distributed across the west, central and eastern basins without population structure. The split between these two main clades was estimated at 1.4 Mya. This cladogenetic event may be associated with the allopatric process promoted by the fragmentation and compartmentalization of hydrographic basins induced by the geological and climatic history of the Mexican Plateau. [ABSTRACT FROM AUTHOR]

Introduction: Anacanthorus silvoi n. sp. (Dactylogyridae, Anacanthorinae) is described from the gills of Hoplias aff. malabaricus (Bloch, 1794) from the Salgado River, Ceará state, Brazil. Materials and Methods: The monogeneans were affixed onto slides using Gray and Wess's medium for examination of their sclerotized structures. For analysis of internal organs, a single specimen was preserved in 5% formalin, stained with Gomori's trichrome, and mounted in Gray and Wess's medium. Results: Anacanthorus silvoi n. sp. is characterized by having a short broad tube MCO with a medial constriction (i.e., MCO with distal region wider than the proximal region, and flexed lateral flap in the distal region in A. cururutuiensis and a MCO with a small projection in the form of a hook in the distal region in A. siphonocommus). Conclusions: The present study corroborates previous studies that the absence of an accessory piece is a characteristic shared by all Anacanthorus members parasites of Erythrinidae. [ABSTRACT FROM AUTHOR]

The Yujiang River lies within the Indo-Burma biodiversity hotspot, a large conservation internationaldesignated biodiversity hotspot in tropical Asia that supports some of the most diverse and unique ecosystems on the planet. Despite the extraordinary endemism in its 33 terrestrial ecoregions, there is little information about its freshwater fish biodiversity. Based on our field investigations and an extensive review of the literatures, we identified 137 fish species (including two non-native species), representing 9 orders, 26 families and 88 genera, that are distributed in the Yujiang River and its drainage basin. According to the International Union for Conservation of Nature (IUCN) criteria, six of these species (Anguilla japonica, Cyprinus carpio, Luciocyprinus langsoni, Pseudohemiculter dispar, Ptychidio jordani, and Cranoglanis bouderius), qualify for recognition as Threatened Species. Overfishing, water flow diversions and modifications, and the impacts of non-native species are the greatest threats to freshwater fish biodiversity in the Yujiang River. We recommend the adoption and enforcement of additional protected areas, improvement in approaches to sustainable fishery management, much better control of non-native species, and an improvement in and the expansion of fish life-history research. Our study contributes recommendations for the better protection of freshwater fish biodiversity and the development of sustainable fisheries in the Yujiang River. [ABSTRACT FROM AUTHOR]

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Dissolved organic carbon (DOC) is a complex mixture of molecules that varies in composition based on origin as well as spatial and temporal factors. DOC is an important water quality parameter as it regulates many biological processes in freshwater systems, including the physiological function of the gills in fish. These effects are often beneficial, especially at low pH where DOCs mitigate ion loss and protect active ion uptake. DOCs of different compositions and quality have varied ionoregulatory effects. The molecular variability of DOCs can be characterized using optical and chemical indices, but how these indices relate to the physiological effects exerted by DOCs is not well understood. We tested the effects of five naturally sourced DOCs, at both pH 7 and pH 4, on transepithelial potential (TEP) (a diffusion potential between the blood plasma and the external water) in rainbow trout. The five chosen DOCs have been well characterized and span large differences in physicochemical characteristics. Each of the DOCs significantly influenced TEP, although in a unique manner or magnitude which was likely due to their physicochemical characteristics. These TEP responses were also a function of pH. With the goal of determining which physicochemical indices are predictive of changes in TEP, we evaluated correlations between various indices and TEP at pH 7 and pH 4. The indices included: specific absorbance coefficient at 340 nm, molecular weight index, fluorescence index, octanol–water partition coefficient, molecular charge, proton binding index, % humic acid-like, % fulvic acid-like, and % protein-like components by parallel factor analysis on fluorescence data (PARAFAC). Our results demonstrate the novel finding that there are three particularly important indices that are predictors of changes in TEP across pHs in rainbow trout: specific absorbance coefficient at 340 nm, octanol–water partition coefficient; and proton binding index. [ABSTRACT FROM AUTHOR]

This research evaluated the suitability of commercially available larval feeds, Otohime B2 (OB2), Aller Infa (AI), and Aqua Start (AS), and one Experimental Feed (EF), for the weaning of largemouth bass (Micropterus salmoides), LMB. Feeds were presented with various ?-3 fatty acid levels/bioavailability (high in OB2 and AI), fat percentage (high in OB2 and AS), free amino acid and short peptide (FAA + SP) levels (high in OB2), and various soluble protein (SPR) levels (high in AS and EF). Fish were co-fed Artemia plus OB2 from the 19th to 22nd day post-hatching (DPH), then Artemia in addition to one of the four above diets for seven days, with complete Artemia removal on the 30th DPH. Fish were sampled on the 32nd DPH. Morphometry, digestive enzyme activities, hormonal status, skeleton, muscle development, and potentially pathogenic Flavobacterium spp. levels were estimated. Survival was high (96% or more) in all the weaning regimes. Weaning to OB2 was linked to a fast fish growth rate (14.29%/day), while both OB2 and AI supported the skeleton development. Weight gain correlated with total fat, ash levels, free amino acids, and short peptide levels in the diet. Larvae weaned to soluble proteinrich AS and EF showed the lowest fish weight gain and skeleton development, and lower growth of potentially pathogenic Flavobacterium spp. This research suggests that the weaning diets for largemouth bass should have a balanced protein content and quality while allowing for the inclusion of fewer marine ingredients. [ABSTRACT FROM AUTHOR]

The term 'microplastics' is defined as a category of pollutants that are highly prevalent in aquatic environments and have the potential to exert adverse consequences on biological systems. In this study, the presence and diversity of microplastics in the muscle, liver and digestive systems of the fish species Barbus anatolicus, Cyprinus carpio and Capoeta tinca, collected from the River Kızılırmak (Nevşehir), were examined in detail. This waterway flows through densely populated areas and empties into the Black Sea. Eighty‐two microplastics were identified in the muscle tissue of the fish, 74 in the liver and 208 in the digestive system. The majority of these microplastics were white and fibre‐shaped. The microplastics detected were of various plastic types, including polyamide, polypropylene, nylon, polyethylene and polyester. The findings of this study demonstrate the significant impact of human activity on the environment, with the presence of microplastics in aquatic ecosystems and living tissues. [ABSTRACT FROM AUTHOR]