Five isonitrogenous (30% protein) diets containing 0, 10, 20, 30 and 40% of
faba bean middling (FBM) instead of soybean meal were investigated for 98 days.
Ten glass aquaria (70-L capacity), were used to stock 10 fish I aquarium of Nile tilapia
fry initially average weight of 0.37 glfish. Fish fed (he diet containing 10% FBM grew
faster than those fed other diets. However, the diets had FBM levels of 20, 30 and 40
% gave similar body weight, gain and specific growth rate being relatively lower value
than the control diet. No significant differences (P>0.05) were observed in protein
efficiency ratio and protein productive value, body contents of protein, ether extract,
ash, and plasma glucose and total lipids. However, fish fed diets containing FBM
levels gave lower concentration of aspartate aminolransferase and alanine
aminotransferase than fish fed the control diet. The level of 10% FBM provided
healthy fish with normal liver structure and optimum gonadal development. However,
liver and gonads structure of fish fed more than 10% FBM resulted in hepatic celts
destruction. sperm resorption in males, and oocyte atresia in females. The 10% level
of FBM was the best economical inclusion level based on incidence cost and profit
index