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Studying scute and fin morphology are advantageous approaches for phylogenetic identification and provide information on biological linkages and evolutionary history that are essential for deciphering the fossil record. Despite this, no prior research has precisely characterized the histological structures of scutes in the common pleco. Therefore, this research investigated the microstructure and organization of bone tissue within the dermal skeleton, including the scutes and fins, in the common pleco, using light microscopy, stereomicroscopy, and scanning electron microscopy. The dermal scutes were organized in a pentagonal shape with denticular coverage and were obliquely aligned with the caudal portion pointing dorsally. The dermal scutes consisted of three distinct portions: the central, preterminal, and terminal portions. Each portion comprised three layers: a superficial bony plate, a basal bony plate, and a mid-plate. Both the superficial and basal bony plates were composed of lamellar bone and lamellar zonal bone, whilst the mid-plate consisted of secondary osteons and woven bone. In the terminal portion, the superficial and basal bony plates became thinner. The pectoral fin consists of spines and rays composed of lepidotrichium (two symmetrical hemi-rays). The spine contained centrifugal and centripetal lamellar and trabecular bones. A centripetal fibrous bone was implanted between the lamellar bones. Besides being oriented in a V shape, the hemi-rays were also composed of thin centrifugal and centripetal lamellar bones and trabecular bones. A fibrous bone was identified between the centrifugal and centripetal bones. The trabecular bone and lamellar bone were made up of bone spicules.

Fatty liver injury is a prevalent condition in most farmed fish, yet the molecular mechanisms underpinning this pathology remain largely elusive. A comprehensive feeding trial spanning eight weeks was conducted to discern the potential of dietary chitosan in mitigating the deleterious effects of a high-fat diet (HFD) while concurrently exploring the underlying mechanism. Growth performance, haemato-biochemical capacity, antioxidant capacity, apoptotic/anti-apoptotic gene expression, inflammatory gene expression, and histopathological changes in the liver, kidney, and intestine were meticulously assessed in Nile tilapia. Six experimental diets were formulated with varying concentrations of chitosan. The first three groups were administered a diet comprising 6% fat with chitosan concentrations of 0%, 5%, and 10% and were designated as F6Ch0, F6Ch5, and F6Ch10, respectively. Conversely, the fourth, fifth, and sixth groups were fed a diet containing 12% fat with chitosan concentrations of 0%, 5%, and 10%, respectively, for 60 days and were termed F12Ch0, F12Ch5, and F12Ch10. The results showed that fish fed an HFD demonstrated enhanced growth rates and a significant accumulation of fat in the perivisceral tissue, accompanied by markedly elevated serum hepatic injury biomarkers and serum lipid levels, along with upregulation of pro-apoptotic and inflammatory markers. In stark contrast, the expression levels of nrf2, sod, gpx, and bcl-2 were notably decreased when compared with the control normal fat group. These observations were accompanied by marked diffuse hepatic steatosis, diffuse tubular damage, and shortened intestinal villi. Intriguingly, chitosan supplementation effectively mitigated the aforementioned findings and alleviated intestinal injury by upregulating the expression of tight junction-related genes. It could be concluded that dietary chitosan alleviates the adverse impacts of an HFD on the liver, kidney, and intestine by modulating the impaired antioxidant defense system, inflammation, and apoptosis through the variation in nrf2 and cox2 signaling pathways.

This study explored the growth efficiency and the intracellular pathways by which Cnicus benedictus extract (CBE) acts. It investigated the antioxidant effects and efficacy of CBE as a fish supplement in attenuation of Aeromonas hydrophila in Oreochromis niloticus fish. Mono-sex Nile tilapia fish (n = 225) were randomly allocated to five groups in triplicate aquaria (n = 3 tanks per group, 15 fish per tank, with 120 L of water per tank) with a daily water exchange rate of 20%. After adaption for 2 weeks and body weight measuring, the experimental groups were fed isonitrogenous and isocaloric diets with different dosages of the ethanolic extract of C. benedictus for 10 weeks. The five groups were identified as the control group (CBE0.0), which was fed on the basal diet, while the second (CBE0.1), the third (CBE0.2), the fourth (CBE0.4), and the fifth (CBE0.6) groups were fed the basal diet supplemented with 0.1%, 0.2%, 0.4%, and 0.6% of C. benedictus extract, respectively. After the 10-week feeding trial was completed, the fish were inoculated with the PCR-identified pathogenic A. hydrophila in a challenge trial which lasted 15 days. A. hydrophila, one of the septicemic bacteria, causes severe economic losses, high mortality rates, and hemorrhages in Nile tilapia and other cultured freshwater fishes worldwide. The CBE was found to significantly increase the body mass, weight gain, and the specific growth rate, as well as the protein efficiency ratio of the fish. Increased survival percentage, accompanied by post challenge lymphocytosis with decreased liver enzyme levels, increased total protein, and improved kidney function markers were also seen. Additionally, CBE supplementation showed significant increases in phagocytic activity, phagocytic index, and lysosomal activity post challenge, accompanied by increases in antioxidant activity and the mRNA expression of cytokines genes hsp70 and tlr7 mRNA. The desirable effects of CBE treatment were confirmed by a histopathological examination of the height of intestinal villi and enterocytes lining the middle intestine and increases in the size of liver cells. We conclude that CBE increases the growth performance and modulates the antioxidant, inflammatory, stress, and immune-related genes in Nile tilapia. Moreover, the dietary inclusion of 0.42–0.47% CBE showed a better protective effect with the A. hydrophila challenge.

Olive leaves are an immense source of antioxidant and antimicrobial bioactive constituents. This study investigated the effects of dietary incorporation of olive leaf extract (OLE) on the growth performance, hematobiochemical parameters, immune response, antioxidant defense, histopathological changes, and some growth- and immune-related genes in the common carp (Cyprinus carpio). A total of 180 fish were allocated into four groups with triplicate each. The control group received the basal diet without OLE, while the other three groups were fed a basal diet with the OLE at 0.1, 0.2, and 0.3%, respectively. The feeding study lasted for 8 weeks, then fish were challenged with Aeromonas hydrophila. The results revealed that the group supplied with the 0.1% OLE significantly exhibited a higher final body weight (FBW), weight gain (WG%), and specific growth rate (SGR) with a decreased feed conversion ratio (FCR) compared to the other groups (p < 0.05). An increase in immune response was also observed in the fish from this group, with higher lysosome activity, immunoglobulin (IgM), and respiratory burst than nonsupplemented fish, both before and after the A. hydrophila challenge (p < 0.05). Similarly, the supplementation of the 0.1% OLE also promoted the C. carpio’s digestive capacity pre- and post-challenge, presenting the highest activity of protease and alkaline phosphatase (p < 0.05). In addition, this dose of the OLE enhanced fish antioxidant capacity through an increase in the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) and decreased hepatic lipid peroxidation end products (malondialdehyde—MDA), when compared to the control group, both pre- and post-infection (p < 0.05). Concomitantly with the superior immune response and antioxidant capacity, the fish fed the 0.1% OLE revealed the highest survival rate after the challenge with A. hydrophila (p < 0.05). A significant remarkable upregulation of the hepatic sod, nrf2, and protein kinase C transcription levels was detected as a vital approach for the prevention of both oxidative stress and inflammation compared to the infected unsupplied control group (p < 0.05). Interestingly, HPLC and UPLC-ESI-MS/MS analyses recognized that oleuropein is the main constituent (20.4%) with other 45 compounds in addition to tentative identification of two new compounds, namely oleuroside-10-carboxylic acid (I) and demethyl oleuroside-10-carboxylic acid (II). These constituents may be responsible for the OLE exerted potential effects. To conclude, the OLE at a dose range of 0.66–0.83 g/kg w/w can be included in the C. carpio diet to improve the growth, antioxidant capacity, and immune response under normal health conditions along with regulating the infection-associated pro-inflammatory gene expressions, thus enhancing resistance against A. hydrophila.

The ameliorative effects of Spirulina and Saccharomyces cerevisiae (S. cerevisiae) against fipronil toxicity in Nile tilapia fish were investigated. Fipronil is a kind of pesticide that is widely used in agriculture, thus this trial was conducted to evaluate the effect of fipronil on growth related parameters (final body weight, feed intake, weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio), hematology related parameters (RBCs, WBCs, hemoglobin, packed cell volume, and deferential leukocytic count), biochemistry related parameters (alanine aminotransferase, aspartate aminotransferase, total protein, albumin, urea, and creatinine), histopathology of liver, intestine, gills, and spleen, and gene expression of antioxidants, stress, inflammatory, apoptotic, and related to junction proteins genes as SOD and GPx, COX II, TNF-α, Casp-3, and Claudin-3, respectively, in Nile tilapia (Oreochromis niloticus). Four hundred and five Nile tilapia fish were distributed in a glass aquarium into nine groups according to the Spirulina and S. cerevisiae supplemented diets, with or without fipronil contaminated water. The classified groups are control, Sc: S. cerevisiae (4 g/Kg diet), Sp: Spirulina (1 g/100 g diet), Fb1: 0.0021 mg fipronil/L, ScFb1: S. cerevisiae (4 g/Kg diet) with 0.0021 mg fipronil/L, SpFb1: Spirulina (1 g/100 g diet) with 0.0021 mg fipronil/L, Fb2: 0.0042 mg fipronil/L, ScFb2: S. cerevisiae (4 g/Kg diet) with 0.0042 mg fipronil/L, and SpFb2: Spirulina (1 g/100 g diet) with 0.0042 mg fipronil/L. The results of the present investigation indicated the negative effect of fipronil on the growth performance parameters of Nile tilapia, which was confirmed by the results of hematology, biochemistry, and histopathology. In addition, the results of gene expression of antioxidants, stress, inflammatory, and apoptotic genes indicate the genotoxicity of fipronil. However, these negative effects were ameliorated by Spirulina and Saccharomyces dietary supplementation.

The present study evaluated the enhancement of the growth rate, intestinal health, immune-related genes, and resistance against suboptimal water temperature in common carp (2.01 ± 0.02 g) by dietary paraprobiotics. Fish were fed dietary heat killed Lactobacillus plantarum (LP20) at 0 (control), 50, and 100 mg/kg for 2 months. After the feeding trial fish were exposed to suboptimal water temperature averaged 13.22 ± 0.44 °C for 48 h. The final body weight, weight gain, specific growth rate, and feed conversion ratio of fish fed LP20 at 100 mg/kg were significantly enhanced (P < 0.05). The villi length and width were increased in fish fed LP20 at 50 and 100 mg/kg when compared to the control (P < 0.05). The crypt depth was increased by increasing LP20 in a dose dependent manner with the highest value in the group of fish fed 100 mg/kg (P < 0.05). The number of goblet cells showed higher number in fish fed LP20 at 50 and 100 mg/kg than the control group (P < 0.05). The expression of catalase (CAT) gene did not show any changes in transcription before the thermal stress however after thermal stress fish fed 50 mg/kg had upregulated CAT followed by those fed 100 mg/kg. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) gene expressions showed upregulations in fish fed 50 mg/kg before the thermal stress but after the thermal stress fish fed 100 mg/kg had the highest level of mRNA transcriptions for GPx and SOD genes. In the same manner, the expression of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin 10 (IL-10) were significantly upregulated in fish fed LP20 at 50 mg/kg before the thermal stress whereas the expression of these genes was upregulated in fish fed 100 mg/kg. In conclusion, using LP20 at 50−100 mg/kg resulted in enhancing the growth rate, intestinal morphometry, immune and antioxidative related genes. Accordingly, common carp showed high resistance against suboptimal water temperature stress.

The present study evaluated the possible synergistic impacts of sodium butyrate and Spirulina platensis as a feed additive on growth performance, carcass composition, blood health, and intestinal histomorphology of Nile tilapia (Oreochromis niloticus). A control and three treated diets were supplemented with sodium butyrate (SB) 350 mg, Spirulina platensis (SP) 1g and a mixture of 350 mg SB and 1g SP/kg diet (SB/SP) respectively, were fed for monosex Nile tilapia (12.5± 0.50 g, n=120) for two months. The results revealed higher growth performance (final weight, weight gain, weight gain rate, SGR and PER) compared to control group (CG) (P

Ammonia is a critical hazardous nitrogen metabolic product in aquaculture. Despite trials for its control, ammonia intoxication remains one of the most critical issues to overcome. In this study, we explored the modulatory effect and potential mechanism by which Yucca schidigera extract (YSE) can ameliorate ammonia intoxication-induced adverse effects on tilapia health and metabolism. A total number of 120 Nile tilapia were evenly assigned into four groups with three replicates each. The first group served as normal control group; the second group was exposed to ammonia alone from the beginning of the experiment and for four weeks. The third group was supplied with YSE in water at a dose of 8 mg/L and exposed to ammonia. The fourth group was supplied with YSE only in water at a dose of 8 mg/L. YSE supplementation succeeded in improving water quality by reducing pH and ammonia levels. Moreover, YSE supplementation markedly alleviated chronic ammonia-induced adverse impacts on fish growth by increasing the final body weight (FBW), specific growth rate (SGR), feed intake and protein efficiency ratio (PER) while reducing the feed conversion ratio (FCR) via improvements in food intake, elevation of hepatic insulin-like growth factor (ILGF-1) and suppression of myostatin (MSTN) expression levels with the restoration of lipid reserves and the activation of lipogenic potential in adipose tissue as demonstrated by changes in the circulating metabolite levels. In addition, the levels of hepato-renal injury biomarkers were restored, hepatic lipid peroxidation was inhibited and the levels of hepatic antioxidant biomarkers were enhanced. Therefore, the current study suggests that YSE supplementation exerted an ameliorative role against chronic ammonia-induced oxidative stress and toxic effects due to its free radical-scavenging potential, potent antioxidant activities and anti-inflammatory effects.