Plant-derived bioactive compounds with promising nutritional and therapeutic attributes (phytogenics) are among the top priorities in the aquaculture sector. Therefore, the impact of thymol (Thy) and/or thymoquinone (ThQ) on the growth, immune response antioxidant capacity, and Aeromonas sobria (A. sobria) resistance of Nile tilapia was investigated. Four fish groups were fed a control diet and three basal diets supplemented with 200 mg/kg diet of Thy or ThQ and a blend of both Thy and ThQ at a level of 200 mg/kg diet each. At the end of the feeding trial (12 weeks), the tilapias were challenged intraperitoneally with virulent A. sobria (2.5 × 10⁸ CFU/mL) harboring aerolysin (aero) and hemolysin (hly) genes. The results revealed that tilapias fed diets fortified with a combination of Thy and ThQ displayed significantly enhanced growth rate and feed conversion ratio. Notably, the expression of the genes encoding digestive enzymes (pepsinogen, chymotrypsinogen, α-amylase and lipase) and muscle and intestinal antioxidant enzymes (glutathione peroxidase, catalase and superoxide dismutase) was significantly upregulated in Thy/ThQ-fed fish. An excessive inflammatory response was subsided more prominently in the group administrated Thy/ThQ as supported by the downregulation of il-β, il-6 and il-8 genes and in contrast, the upregulation of the anti-inflammatory il-10 gene. Remarkably, dietary inclusion of Thy/ThQ augmented the expression of autophagy-related genes, whilst it downregulated that of mtor gene improving the autophagy process. Furthermore, Thy/ThQ protective effect against A. sobria was evidenced via downregulating the expression of its aero and hly virulence genes with higher fish survival rates. Overall, the current study encouraged the inclusion of Thy/ThQ in fish diets to boost their growth rates, promote digestive and antioxidant genes expression, improve their immune responses and provide defense against A. sorbia infections with great economic benefits.

In modern aquaculture, enriching Nile tilapia’s diet with omega-3 poly-unsaturated fatty acids (PUFAs) not only plays an important role in its general health but also fortifies its fillet with omega-3-PUFAs. However, the major challenge affecting their delivery is their high instability due to oxidative deterioration. Thus, the prospective incorporation of omega-3-PUFAs into nanocarriers can enhance their stability and bioactivity. In this regard, the effect of reformulated omega-3-NPs was investigated on Nile tilapia’s performance, flesh antioxidant stability, immunity, and disease resistance. Four fish groups supplemented with omega-3-PUFAs-loaded nanoparticles (omega-3 NPs) at levels of 0, 1, 2, and 3 g/kg diet and at the end of feeding trial fish challenged with Aeromonas hydrophila. Fish performance (weight gain and feed conversion) was improved in groups supplemented with omega-3-NPs (2 and 3 g/kg diet). The deposition of omega-3-PUFAs in fish flesh elevated with increasing dietary omega-3-NPs. Simultaneously the oxidative markers (H₂O₂, MDA, and reactive oxygen species) in fish flesh were reduced, especially with higher omega-3-NPs. Post-challenge, downregulation of IL-1β, IL-6, IL-8, TNF-α, and caspase-1 were noticed after dietary supplementation of omega-3-NPs. Moreover, mRNA expression of autophagy-related genes was upregulated while the mTOR gene was downregulated with higher omega-3 NPs levels. Lower expression of A. hydrophila ahyI and ahyR genes were detected with omega-3 NPs supplementation. In conclusion, omega-3-NPs application can fortify tilapia flesh with omega-3-PUFAs and augment its performance, immunity, and disease resistance against Aeromonas hydrophila.

Aflatoxin B1 (AFB1) contamination of aquaculture feed poses serious health risks to fish and consumers. In this study, the efficacy of a novel anti‐mycotoxin agent specific for aquatic species (AM‐AQ) containing bentonite, sepiolite, and orange peel meal ( Citrus Sinensis ) in alleviating AFB1 toxicity in Nile tilapia ( Oreochromis niloticus ) was evaluated. Fish were fed a basal diet as a control group and diets containing AFB1 (50 μg/kg), AM‐AQ (3 g/kg), or a combination of both for 6 weeks. AFB1 exposure significantly reduced growth, altered hematological parameters, protein profile, and digestive enzyme activities ( p < 0.05), and suppressed respiratory burst activity ( p < 0.001). It also altered the expression of liver and kidney function enzymes, lysozyme, and pro‐inflammatory cytokines and generated oxidative stress ( p < 0.05, p < 0.01). AM‐AQ supplementation effectively counteracted these adverse effects by restoring these parameters to control levels. Notably, AM‐AQ reduced AFB1 residues in the musculature by 99.6% after 6 weeks ( p < 0.001). Histopathological analysis revealed severe liver, spleen, and intestinal damage in the group exposed to AFB1, which was markedly ameliorated by AM‐AQ treatment ( p < 0.05). These results demonstrate that the AM‐AQ is a promising feed additive for protecting Nile tilapia against AFB1 toxicity and for reducing AFB1 transfer to edible tissues. Further research is required to optimize its application in aquaculture.

The current study is a pioneer trial to verify the effectiveness of Petroselinum crispum (parsley) nanoparticles (PNPs) for fortifying physiological and biochemical biomarkers in female African catfish postexposure to bisphenol A (BPA) toxicity. The aim of this experiment is to verify the influence of PNPs for mitigating serum hemato‐biochemical alterations as well as antioxidant enzyme, and hormonal changes induced by BPA toxicity in the hepatic and ovarian tissues. Fish were equally allocated into four groups: group I as a control without any treatments, group II received a commercial diet + PNPs (4 g/kg diet). In group III, fish were subjected to 1/10 LC50 (BPA) (1.43 µg/L), while in group IV, fish got 1/10 LC50 BPA (1.43 µg/L) + PNPs (4 g/kg diet) for 60 consecutive days. Exposure to BPA showed macrocytic hypochromic anemia and leukopenia, and a noticeable elevation in glucose, alanine amino‐transferase (ALT), aspartate aminotransferase (AST), ALP, urea, creatinine, cortisol, cholesterol, and testosterone (T) hormone. Furthermore, serum AchE, estradiol (E2), follicle‐stimulating hormone (FSH), luteinizing hormone (LH), globulin, albumin, and total proteins were significantly decreased in a BPA‐exposed group. Alternatively, activities of superoxide dismutase (SOD), lipid peroxidation (LPO), and catalase (CAT) were notably augmented in the hepatic tissue and ovaries of the BPA‐supplemented fish. While total antioxidant capacity (TAC) and reduced glutathione (GSH) levels decreased in the equal tissues of exposed fish. PNPs‐supplemented diets in combination with BPA alleviated its destructive effects on the tested parameters. In conclusion, the results proved that BPA is an endocrine hormonal disruptor that induces imbalances in blood profile, hepato–renal indicators, and stress parameters, besides the occurrence of oxidative damage and reproductive dysfunction. Interestingly, PNPs have a protective role in attenuating BPA toxicity and modulating all the measured biomarkers, as well as improving the fertility of female Clarias gariepinus .

Ectoparasitic infestations present a significant challenge to aquaculture health management by disrupting the oxidative stress balance, immune defense mechanisms, and energy metabolism of European seabass ( Dicentrarchus labrax ). These effects are further influenced by seasonal environmental changes that impact both host physiology and parasite prevalence. This study assessed seasonal changes in oxidative stress, immune response, energy metabolism, growth, and tissue damage in a total of 200 European seabass collected seasonally from a marine fish farm in Damietta, Egypt. Fish showed increased oxidative stress and immune activity in the autumn, the winter, and the spring, with glutathione (GSH) peaking in the spring, while malondialdehyde (MDA) and nitric oxide (NO) levels increased in autumn and winter. Immune markers like immunoglobulin M (IgM) and lysozyme were significantly elevated in winter and spring, while interleukin-1β ( il-1β ) increased during autumn and winter. Liver energy biomarkers increased during autumn and spring compared to summer and winter. Histopathological lesions, including necrosis, hemorrhage, and inflammation, were found especially during temperature extremes. Principal component analysis (PCoA) revealed biomarker clusters linked to parasite loads and environmental stress. Seasonal infestations induce oxidative damage, immunological problems, and metabolic changes that compromise fish health. These findings highlight the significance of employing oxidative, immunological, and metabolic biomarkers as indicators of ectoparasitic stress, enabling seasonal health management measures to improve fish welfare and mitigate production losses in aquaculture.