Replacement of fishmeal with processed meal from knife fish Chitala ornata in diets of juvenile Nile tilapia Oreochromis niloticus

A 60-day feeding trial was conducted to assess the effects of processed meal from knife fish Chitala ornata (KFM) as fishmeal replacement in diets of Nile tilapia Oreochromis niloticus juveniles. Five iso-nitrogenous (36.4% in dry matter) and isolipidic diets (8.6% in dry matter) with 0 (D1), 25 (D2), 50 (D3), 75 (D4) and 100% (D5) KFM inclusions were prepared. With a stocking density of 15 fish (0.59 ± 0.01 g) per tank, tilapia juveniles were distributed randomly in fifteen 30-L tanks. Results indicate a significant increase (P < 0.05) in the percent average weight gain, specific growth rate, and feed intake with increasing KFM inclusion up to the level of 75%. There were no adverse effects observed in both blood profile and carcass composition of the tilapia. Hepatosomatic index of fish significantly increased (P < 0.05) when KFM was included into the diet of tilapia, compared to those fed D1. Viscerosomatic indices were not significantly different (P > 0.05) among treatments. Results of hepatic histopathology showed absence of tumors, lesions and parenchymal inflammation in all treatments. However, mild cell membrane lysis and mild and mild to moderate apoptosis were evident in liver samples. Based on the results, KFM can partially and completely replace dietary protein from fishmeal. Moreover, D4 (75% KFM) is considered the optimal KFM replacement level for Nile tilapia juveniles.