Effects of Different Levels of Dietary Vitamin C on Growth Performance, Digestive Enzymes Activity and Blood Stress Factors of Nile Tilapia (Oreochromis Niloticus) Under Sub-Lethal Toxicity of Malathion

Malathion is one of the agricultural organophosphate pesticides used in agriculture that may be found in aquaculture centers. The aim of this study was to investigate the effects of different levels of dietary vitamin C on improving the situation of growth, digestive enzymes activity and blood stress factors of Nile Tilapia (Oreochromis Niloticus) under sub-lethal toxicity of malathion.

In this experimental study, 180 Nile tilapia with weight average of 12.5±5g were subjected to 25% concentrations of Lc50 96h of malathion for 28 days and during this period, the fishes were fed with different levels of vitamin C (0, 300, 600, and 900mg/kg of feed). Data were analyzed by Duncan's new multiple range test and one-way analysis of variance through SPSS 24 software.

The weight gain and specific growth rate of fish fed by the highest vitamin level (900mg/kg of feed) were significantly higher than other groups (p<0.05), while the feed conversion ratio in the fish under mentioned treatment significantly decreased compared to other treatments. Trypsin and chymotrypsin digestive enzyme activities were significantly increased in treatments of 600 and 900mg/kg vitamin C in diet, respectively. The activity of other enzymes at different concentrations of vitamin C in the diet did not show a significant difference (p>0.05). Blood glucose level was significantly higher in control treatment in comparison to the other treatments.

Vitamin C as an anti-stress agent reduces the stress in Nile tilapia subjected by Malathion pesticides and improve the metabolic status and growth performance of Nile tilapia.