Potential of crab meal as a protein substitute for fish meal in diets for mudfish Heterobranchus longifilis juveniles

A study aimed at evaluating the suitability of crab meal as a potential substitute for dietary fishmeal protein for mudfish (Heterobranchus longifilis) juvenile was carried out. Fishmeal (FM) and crab meal (CM) protein sources were used separately to prepare diets containing 30, 35 and 40% crude protein (CP). The diets were fed to fish at 5% body weight for 70 days in plastic aquaria. Crab meal at 30% CP level showed a performance of approximately 56.6% (percent weight gain), 50% (specific growth rate, protein efficiency ratio and apparent net protein utilization) of FM containing diet of 30% CP but was similar in fish condition, 0.62 ± 0.005 and 0.66 ± 0.005 for CM and FM diets. Fish survival was 100% for all experimental diets. The feed conversion ratio was appreciable, 4.50 ±1.38 for CM compared to 2.60 ± 0.65 and 1.94 ± 0.65 for 30% and 35% protein fishmeal diets. Inadequate essential amino acid balance and digestibility could be responsible for the reduced performance of crab meal compared to fish meal. Crab meal has potentials and future trails on partial replacement of FM could reveal improved performance on H. longifilis.