Abstract
Background:
The aquaculture industry is actively seeking alternatives to antibiotics to improve fish's growth, immunity, and overall health. Natural products have been found to contain specific metabolites with immunomodulatory properties.

Aim:
The objective of this experiment was to evaluate the effects of dietary dimethyl itaconate (DMIC) on growth, feed utilization, blood hematology and metabolites, antioxidant capacity, and inflammation biomarkers of Nile tilapia following an Aeromonas hydrophila infection.

Methods:
Over 56 days, the fish (20.97 ± 0.33g, n=200) were fed a basal diet supplemented with different levels of DMIC: 0 (DMIC0), 50 (DMIC50), 100 (DMIC100), and 200 (DMIC200) mg/kg of diet.

Results:
All the groups receiving DMIC showed improved growth indices (FBW, SGR, WG) and feed intake compared to the untreated group (p<0.05), while FCR was not affected (p>0.05). The fish fed with DMIC exhibited significantly improved levels of glutathione, RBCs, neutrophils, hemoglobin, and hematocrit in their blood (p<0.001). Interestingly, the groups fed with DMIC also showed a dose-dependent increase in serum levels of IgM (p<0.05), glucose, total protein, albumin, nitric oxide, and lysosome activity. All the DMIC-treated groups displayed greater phagocytic activity, while serum levels of MDA, creatinine, ALP, ALT, AST, and uric acid were significantly decreased compared to the control group (p<0.01). Fish fed with DMIC also exhibited significantly reduced serum levels of TNF-α, IFNγ, and IL-4 (p<0.05). Furthermore, fish infected with A. hydrophila and fed with DMIC for 15 days showed higher survival rates compared to the untreated groups.

Conclusion:
In conclusion, dietary supplementation with DMIC at levels of 100 or 200 mg/kg of diet may be a novel strategy to enhance the health, immunity, blood profile, antioxidant capacity, and resistance to A. hydrophila in Nile tilapia fish.

Key words: Dimethyl itaconate; Fish; Performance; Health; Immunity and inflammation.