Evaluation of the influence of housefly maggot meal (magmeal) diets on catalase, glutathione S-transferase and glycogen concentration in the liver of Oreochromis niloticus fingerling.

Influence of housefly maggot meal (magmeal) diets on the activities of catalase (CAT), glutathione S-transferase (GST) and glycogen concentration in liver of Tilapia Oreochromis niloticus fingerling was evaluated. Triplicate groups of fifteen fish (initial average weight 2.0+/-0.1 g) were fed eight weeks with seven test diets (in average 36% crude protein, dry matter) formulated by replacing fish meal with magmeal. Percentage body weight gain (591-724.46%), food conversion ratio (1.05-1.22) and standard growth rate (3.45-3.76) in all feeding groups were not significantly different (P<0.05). No significant difference (P<0.05) was observed in liver glycogen reserve (175.27-236.88 micromol g(-1)) among the fish groups. Hepatic catalase activity also did not differ significantly. However, elevated glutathione S-transferases activities were observed when fish received higher dietary magmeal concentration. This might have been temporary with no real physiological implication when appraised by the growth responses. These results indicate that magmeal was well utilized by the fish and its incorporation into tilapia diets seems to have no oxidative stress generating effect on fish metabolism and may not be containing any compound that stimulates the generation of reactive oxygen species. Magmeal can effectively be used as an alternative protein source in tilapia fingerling production.