The present study investigated the effects of dietary supplementation of nanocurcumin (NCur = 150 ppm) in African catfish feed for 15 days along with two doses of florfenicol—a therapeutic dose (FFC1 = 10 mg/kg.BW) and a high dose (FFC2 = 30 mg/kg.BW). Serum biochemical parameters and histopathological changes in liver and kidney tissues were determined post-feeding. Additionally, fish were experimentally challenged with a virulent strain of Aeromonas veronii to explore the fish’s capacity to resist infections. Results indicated that the serum level of total protein was significantly elevated in the FFC2 + Ncur group compared with control, Ncur, and FFC2 groups. Total protein level was also higher in FFC1 + Ncur compared with that of the FFC1 group. Moreover, feeding NCur, FFC1 + Ncur, and FFC2 + Ncur resulted in a significant increase in globulin levels compared to control, FFC1, and FFC2-Fed groups. However, the albumin level was unaffected. Serum levels of AST, ALT, ALP, and urea significantly increased in FFC2-fed fish compared to controls indicating liver damage. The higher dosage of FFC2 induced histological alterations in the liver and kidney architecture, represented by a rupture of the central vein, cytoplasmic vacuolation, hepatocytes necrosis, and severe inflammation. Surprisingly, NCur inclusion improved most of the altered biochemical parameters and mitigated FFC-induced histological damage in the hepatic and renal tissues. Similarly, fish that were fed a combination of both FFC and Ncur showed a higher resistance when exposed to A. veronii infection, as the mortality rates were significantly lower than those of the control group. Our findings indicated that incorporating NCur into the diet can have multiple benefits for the sustainable aquaculture of African catfish. These advantages encompass mitigating drug-induced damage to the liver and kidney tissues, augmenting the therapeutic efficacy of FFC in a synergistic manner and providing protection against A. veronii infections.

Objective: During Egypt's hot summer season, Aeromonas veronii infection causes catastrophic mortality on Nile Tilapia Oreochromis niloticus farms. Egypt is ranked first in aquaculture production in Africa, sixth in aquaculture production worldwide, and third in global tilapia production. This study aimed to investigate, at the molecular level, the early innate immune responses of Nile Tilapia to experimental A. veronii infection. Methods: The relative gene expression, co-expression clustering, and correlation of four selected immune genes were studied by quantitative real-time polymerase chain reaction in four organs (spleen, liver, gills, and intestine) for up to 72 h after a waterborne A. veronii challenge. The four genes studied were nucleotide-binding oligomerization domain 1 (NOD1), lipopolysaccharide-binding protein (LBP), natural killer-lysin (NKL), and interleukin-1 beta (IL-1β). Result: The four genes showed significant transcriptional upregulation in response to infection. At 72 h postchallenge, the highest NOD1 and IL-1β expression levels were recorded in the spleen, whereas the highest LBP and NKL expression levels were found in the gills. Pairwise distances of the data points and the hierarchical relationship showed that NOD1 clustered with IL-1β, whereas LBP clustered with NKL; both genes within each cluster showed a significant positive expression correlation. Tissue clustering indicated that the responses of only the gill and intestine exhibited a significant positive correlation. Conclusion: The results suggest that NOD1, LBP, NKL, and IL-1β genes play pivotal roles in the early innate immune response of Nile Tilapia to A. veronii infection, and the postinfection expression profile trends of these genes imply tissue-/organ-specific responses and synchronized co-regulation.