Impact of Dietary Nano-Chitosan and Lead Exposure on Growth, Chemical Composition, Biochemical Parameters, and Histology in Thin-Lipped Mullet (Liza ramada, Risso, 1826)

Two months of feeding experimental was established to assess the impacts of dietary chitosan nanoparticles (CSNP's) and lead (Pb)-contaminated diets on growth, immunological, biochemical, and histological parameters, as well as the proximate analysis of the whole-body composition in thin-lipped mullet (Liza ramada). A total of 300 thin-lipped mullet (3.75 ± 0.20g) were allocated into five treatments (T), each one fed on a different diet as follows: T1 a basal diet with 30% crude protein and 6% crude lipid (negative control); T2 diets intoxicated with 100μg/ kg of lead (Pb) (CTRP); T3 a diet intoxicated with 100μg/ kg of Pb combined with 1g of CSNP's (Pb100 CSNP's); T4 a diet contaminated with 150μg/ kg of Pb combined with 1g of CSNP's (Pb150 CSNP's); and T5 a diet contaminated with 200μg/ kg of Pb mixed with 1g of CSNP's (Pb200 CSNP's). The L. ramada population was uniformly distributed throughout 15 hapas measuring 0.7m × 0.7m × 1.0m, set in the raceway ponds. The growth performance and survival rate (%) were adversely affected by Pb-contaminated diets; however, CSNP's significantly enhanced these parameters by mitigating Pb toxicity. The serum levels of alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were significantly elevated in the dietary Pb treatment (CTRP). In contrast, the immunological parameters exhibited a notable decrease in total protein, albumin, globulin, LYZ activity, NBT test, and IgM levels. The activities of SOD, catalase, and GPx were diminished with this treatment (CTRP). The dietary treatment of CSNP's and/or Pb, together with their interaction, significantly enhances fish immune responses; however, it negatively impacts crude protein levels and increases fat percent in fish muscles related to the negative control treatment. Consequently, the histological examination revealed that fish exclusively consuming a lead-contaminated diet had severe intestinal degeneration and sloughing of the intestinal villi epithelium, while the liver displayed severe hepatocytic vacuolation and hyperplasia of the hepatic duct. In comparison to the T3 (Pb100 CSNP's), the intestinal length and absorptive area were markedly increased. Additionally, the groups were exposed to Pb (150 and 200µg/ kg, respectively) supplemented with chitosan, demonstrating little vacuolation of hepatocytes with leukocytic infiltration. Dietary CSNP's may have a beneficial effect against lead-induced oxidative stress, hence increasing fish immunity and growth performance in L. ramada.