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The impacts of oregano essential oil and sodium butyrate on the growth performance, hematological, biochemical, immunological, antioxidative, and gene expression profiles of Nile tilapia ( Oreochromis niloticus ) fingerlings were examined in this study. One hundred eighty healthy fingerlings (16.00 ± 2.00 g) were acclimated and accidentally divided into three groups, each further split into three replicates. The groups were fed a basal diet (control) or diets supplemented with 0.5% and 1% oregano essential oil and sodium butyrate for eight weeks (The feed additives were administered continuously throughout an 8-week trial period, simulating a practical feeding strategy that would be feasible during high-risk periods (e.g., post-handling stress, seasonal disease outbreaks). Fish fed the supplemented diets demonstrated significantly greater growth performance, with the oregano 1% + sodium butyrate 1% group achieving the highest final body weight (36.91 ± 0.66 g) and lowest feed conversion ratio (1.32 ± 0.04). Hematological indices, including RBC count, Hb, and PCV, were substantially improved. Biochemical analysis revealed reduced ALT, AST, urea, and creatinine levels alongside elevated total protein and globulin concentrations in treated groups. Immunological and antioxidative parameters, such as WBC count, phagocytic activity, SOD, and GPX, showed significant enhancements, particularly in the oregano 1% + sodium butyrate 1% group. Gene expression analysis exposed upregulation of immune-related (TNF-α, IL-1β) and antioxidative (SOD, GPX) genes in supplemented groups, highlighting their role in enhancing health and stress responses. Post Aeromonas hydrophila infection, the supplemented groups exhibited improved immunity, antioxidative status, and survival. These findings suggest that dietary supplementation with oregano essential oil and sodium butyrate, particularly at 1% inclusion, effectively enhances growth, health status, immunity, and gene expression in Nile tilapia.

This research investigates the effects of dietary supplementation with Ecobiol plus ® (Bacillus amyloliquefaciens CECT5940) on the growth performance, physiological responses, oxidative stress, and immune status of Nile tilapia (Oreochromis niloticus) fingerlings revealed to Aeromonas hydrophila . A total of 525 Nile tilapia fingerlings, averaging 30.00 ± 5.00 g in initial weight, were randomly divided into four groups (control and three experimental groups), each with three replicates of 25 fish. Ecobiol plus ® was integrated in the diet at concentrations of 0.0 (control), 0.1, 0.2, and 0.4 g/kg feed. Fish were fed at 3% of their biomass daily, with biweekly adjustments based on growth. The feeding trial lasted 8 weeks, followed by a 15-day challenge with Aeromonas hydrophila to evaluate immune responses and survival outcomes. The group receiving 0.4 g/kg of Ecobiol plus ® exhibited the most significant improvements in growth performance, including higher weight gain, specific growth rate, and feed conversion efficiency ( p  < 0.05). Blood and biochemical assessments indicated increased hemoglobin, total protein, and globulin levels, reflecting improved physiological and immunological conditions. Additionally, lysozyme activity and phagocytic response were markedly enhanced, demonstrating the probiotic’s immune-boosting potential. Histopathological evaluations revealed reduced gut, gills, and hepatopancreas lesions, especially in groups with higher supplementation levels. Fish in Group T4, fed with 0.4 g/kg Ecobiol plus ® , achieved the best growth performance, with a final weight of 77.96 ± 5.53 g, a weight gain of 42.46 ± 3.18 g, and a specific growth rate (SGR) of 1.51%/day, compared to the control group (T1) with a final weight of 75.26 ± 3.87 g, weight gain of 35.76 ± 2.08 g, and SGR of 1.24%/day. Survival rates considerably increased in the treated groups, with T4 exhibiting the highest rate of 96.00%, followed by T2 (94.68%), T3 (92.00%), and T1 (81.32%). Additionally, the LD50 of A. hydrophila was determined to be 3 × 10⁷ CFU/mL, underscoring the protective effect of Ecobiol plus ® in enhancing fish immunity and resilience against bacterial challenges. These results suggest that Ecobiol plus ® can be a natural, antibiotic-free additive to strengthen growth and disease resistance in Nile tilapia. The optimal inclusion level of Ecobiol plus ® is 0.4 g/kg for maximum benefit.

The optimal water temperature for the normal growth of Nile tilapia is between 26 and 28 °C, and the toxicity of pesticides is strongly related to water temperature. An alternate approach to augmenting the resistance of fish to ambient water toxicity and low water temperature via synbiotic feeding was proposed. In this study, fish were allocated into four groups with 10 fish in each replicate, where they were fed a basal diet or synbiotics (550 mg/kg) and kept at a suboptimal water temperature (21 ± 2 °C). The prepared diets were fed to Nile tilapia for 30 days with or without deltamethrin (DMT) ambient exposure (15 μg/L). The groups were named control (basal diet without DMT toxicity), DMT (basal diet with DMT toxicity), synbiotic (synbiotics without DMT toxicity), and DMT + synbiotic (synbiotics with DMT toxicity). The results displayed upregulated transcription of catalase, glutathione peroxidase, and interferon (IFN-γ) genes caused by DMT exposure and synbiotic feeding when compared with the controls. Moreover, HSP70 and CASP3 genes displayed increased transcription caused by DMT exposure without synbiotic feeding. However, fish fed with synbiotics showed downregulated HSP70 and CASP3 gene expressions. The transcription of IL-1β and IL-8 genes were also decreased by DMT exposure, while fish fed synbiotics showed upregulated levels. DMT exposure resulted in irregular histopathological features in gills, intestine, spleen, and liver tissues, while fish fed synbiotics showed regular, normal, and protected histopathological images. Our results indicated that dietary synbiotics ameliorated histopathological damages in DMT-exposed tilapia through alleviation of oxidative stress and inflammation as well as enhancing the immunity.

Aeromonas hydrophila infection is one of the major diseases that cause inflammation and immunodepression in aquatic animals. Likewise, waterborne toxins are known for their negative impact on the immunity and antioxidant responses of aquatic organisms. In this study, Lactobacillus plantarum (LP20) was incorporated in Nile tilapia, Oreochromis niloticus , diets (50 mg/kg) to investigate its role in the antioxidant capacity, immunity, and anti-inflammation induced by deltamethrin (DLM) toxicity (96-h LC 50 was 14.9 μg/L) and A. hydrophila (LD 50 , 2 × 10 8 CFU/ml). One hundred and twenty healthy fish with an initial weight of 28.21 ± 1.34 g were allotted in 12 glass aquaria (60 L) and divided randomly into four groups (triplicates, 10 fish per aquarium). The control fish neither received LP20 nor were exposed to DLM. The second group of fish was fed the control diet and subjected to DLM (DLM group). The third group of fish was provided with LP20 without DLM toxicity (LP20 group), and the fourth group of fish was fed LP20 and subjected to DLM (DLM + LP20 group). After 30 days, fish were intraperitoneally injected with A. hydrophila . Ten days post infection, the survival rate was lower in fish exposed to DLM than those exposed to LP20. Further, fish fed on LP20 had elevated serum total protein (sTP), albumin (ALB), globulin (GLB), phagocytic index (PI), phagocytic (PA), and lysozyme activities (LZM), but they had lower urea, uric acid bilirubin, creatinine, glucose, aspartate aminotransferase (AST), alkaline phosphatase (ALP), and alanine aminotransferase (ALT) activities after 24 h, 48 h, and 1 week post A. hydrophila challenge. However, fish exposed to DLM had lower sTP, ALB, GLB and higher urea, uric acid, bilirubin, creatinine, glucose, ALT, AST, and ALP after 24 h, 48 h, and 1 week post A. hydrophila challenge. Markedly, after the A. hydrophila challenge, fish exposed to DLM + LP20 displayed upregulated levels of superoxide dismutase ( SOD ), catalase ( CAT ), and glutathione peroxidase ( GPx ) genes. The transcription of interferon gamma ( IFN- γ), interleukin 12 ( IL-12 ), and tumor necrosis factor alpha ( TNF- α) was upregulated in DLM and DLM + LP20 groups. Fish exposed to DLM downregulated interleukin 8 ( IL-8 ) gene expression after A. hydrophila challenge. Further, fish displayed upregulation of heat shock protein 70 ( HSP70 ) gene expression after DLM toxicity. Besides, fish exposed to DLM toxicity and A. hydrophila infection had severe inflammatory features in the liver, spleen, gills, and intestine, while dietary LP20 relieved the inflammatory features. In summary, dietary LP20 relieves Nile tilapia from oxidative stress, immunosuppression, and inflammation induced by DLM and A. hydrophila infection.

This study aimed to detect the impact of Moringa oleifera leaf powder dietary inclusion on the antioxidant and innate immune responses of mono-sex Nile tilapia fingerlings. A total of 180 fingerlings were allocated in a random method into three groups with triplicate each. One group (1 st group) received the control diet (basal diet (BD) free of moringa) and the other groups (2 nd and 3 rd ) fed BD containing M. oleifera leaf powder at 5 and 10% of the diet, respectively. After 6 weeks of feeding, fish were randomly redistributed into four replicates and rested for 24 h. Then, each fish in the first two replicates was injected with 0.2 mL of PBS, while the others were injected with 0.2 mL of A. hydrophila suspension (1.8 × 10 6 CFU/mL). Healthy fish fed on M. oleifera leaf powder showed enhanced immune response manifested by significant increases in phagocytic and lysozyme activities with a marked H/L ratio ( P < 0.05). In addition, significant alterations of the lymphocytic and heterophilic population in circulation with increasing infiltration in tissue such as the spleen were noticed. Also, M. oleifera significantly upregulated the antioxidants, CAT and GPx , proinflammatory cytokines, IL1- β , IL-8 , and IFN- γ relative mRNA levels. On the other hand, following A. hydrophila challenging conditions , M. oleifera caused downregulations of IL1- β , IL-8 , and IFN- γ transcription levels, and also lowered the CAT and GPx mRNA levels. In addition, a marked reduction of leukocytic infiltration plus a significant improvement of the degenerative changes in intestinal architecture has occurred. So, M. oleifera leaf powder can be included in the fish diet to enhance immune response under normal health conditions and lower the infection-associated inflammatory response.

[This corrects the article DOI: 10.3389/fvets.2022.918933.].

The use of feed additives in aquatic animals improves health conditions and well-being under pesticide toxicity. Thus, this study was aimed at evaluating the effect of an immunobiotic mixture (IM) on the growth performance, hemato-biochemistry, and immunity of Nile tilapia exposed to subacute deltamethrin (DMT). Fish were distributed into four groups: groups 1 and 2 were fed a control diet, while groups 3 and 4 were fed IM. Groups 2 and 4 were exposed to DMT (15 μg/L) in rearing water. The results revealed that DMT-exposed fish exhibited significantly lower final body weights, weight gain, specific growth rate, and survival rate ( P  < 0.05), while IM feeding resulted in improved growth performance and survival rate in fish with or without DMT toxicity. After 15 and 30 days, DMT-treated fish showed a significant increase in blood urea and bilirubin as well as hepatic enzymes (alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase) ( P  < 0.05), while supplementation of the IM mixture significantly lowered these levels in Nile tilapia. Blood total protein, globulin, albumin, white blood cells, red blood cells, hemoglobin, phagocytic index, and phagocytic and lysozyme activities were significantly decreased in tilapia subjected to DMT ( P  < 0.05), while supplementation of the IM mixture significantly increased these levels. Fish fed IM without DMT exposure showed the lowest cortisol and glucose levels, while fish exposed to DMT without IM showed the highest levels ( P  < 0.05) after 15 and 30 days. To conclude, IM supplementation exhibited defensive effects against DMT toxicity in Nile tilapia by improving growth performance, hematology, blood biochemistry, and immunity.

Background Fish farming is one of the most productive economies in the world. One of the essential goals in fish production is to minimize processing costs while maintaining and increasing the vital functions, weight and immunity of fish. Objective We conducted this study to explore nanoselenium (Nano‐Se) particles in various feeding schemes. Material and Method Nano‐Se particles incorporated in the basal diet at (0.5 mg/kg diet), and the fish was divided into six groups after adaptation as the follows: The first group was feed daily with a diet containing Nano‐Se (0.5 mg/kg diet); the second group was exposed to a feeding programme in which it has day feeding followed by day of starvation with a diet containing Nano‐Se (0.5 mg/kg diet); the third group was day feeding followed by 2 days of starvation; the fourth group served as a negative control group in which this group was continuous feeding with a basal diet without Nano‐Se; the fifth group was day feeding with the basal diet followed by a day of starvation; and the sixth group was day feeding with basal diet followed by 2 days of starvation. Result Our result revealed that Group 2 showed significant improvement in haematological parameters, red blood cells and haemoglobin with a substantial increase in total protein (p < 0.05) as well as lysosomal and phagocytic activity with considerable upregulation of growth hormone and insulin growth factor 1 in addition to markedly increase in the pro‐inflammatory cytokines. Finally, this study offers the first‐time dietary regime with Nano‐Se supplementation that saves the feeding cost and increases fish welfare and growth. Nanoselenium (Nano‐Se) supplementation with dietary regime that feeding the fish one day followed by one day starvation and soon has the tendency to potentiate the growth efficiency and immunity as well as improvement the growth hormone, insulin growth factors and pro‐inflammatory cytokines. These finding for the first time supported our hypothesis that confirm the Nano‐Se supplementation to the diet of fish with special dietary regime could be useful for aquatic life and economy in decreasing the feeding cost as well as increasing the fish health welfare and growth.

Dietary supplementation of selenium nanoparticles (Se-NPs) at different levels (0, 0.5, 1, and 2 mg kg−1 diet) was evaluated to find out the effects on serum and skin immune responses as well as stress resistance in the red sea bream (Pagrus major). After 45 days of experimental trial, serum and mucosal immune responses were significantly high in fish fed 1 mg Se-NPs kg−1 diet (P < 0.05). In this group, alternative complement pathway, total serum protein, antioxidant activity of catalase enzyme, serum bactericidal activity, serum lysozyme activity, and amounts of skin mucus secretions as well as stress resistance against low salinity stress increased significantly, when compared to fish fed Se-NP-free diet (P < 0.05). Furthermore, fish fed Se-NPs at 2 mg kg−1 diet exhibited higher alternative complement pathway, total serum protein, mucus lysozyme activity, serum and mucus peroxidases, amount of mucus secreted, and tolerance against low salinity stress than the fish fed Se-NP-free diet (P < 0.05). Interestingly, the nitro blue tetrazolium activity in all groups fed with diets supplemented with Se-NPs are significantly higher than Se-NP-free diet (P < 0.05). The present results demonstrate that the dietary supplementation with Se-NPs (mainly from 1 to 2 mg kg−1 level) could be useful for maintaining the overall health status of red sea bream.

A series of Schiff bases 14–25 were designed and synthesized for evaluation of their antibacterial properties against multi-drug resistant bacteria (MDRB). The antibacterial activities of Schiff bases 14–25 showed that most of the synthesized compounds displayed a significant antibacterial activity. Assessment of in silico ADMET properties (absorption, distribution, metabolism, excretion and toxicity) of Schiff bases illustrates that all derivatives showed agreement to the Lipinski’s rule of five. Further enzymatic assay aided by molecular docking study demonstrated that compound 18 is a potent inhibitor of staphylococcus aureus DNA gyrase and dihydrofolate reductase kinases. This study could be valuable in the discovery of new potent antimicrobial agents.