The growth response, nutrient utilization, cost benefits and haematological responses of two hundred and fifty (250) Heterobranchus longifilis fingerlings fed maggot meal based diets were evaluated for 70 days in mini flow through system. Twenty fingerlings were stocked in triplicate in fifteen mini flow through system of plastic tanks of fifty (50) litres capacity and coded MM1 - MM5 in relation to their diet name. Five isonitrogenous (40.0%) and caloric content (2017.S 2092.3kJ/100g) maggot meal based diets namely MM1 O%maggot meal, MM2 25% maggot meal, MM3 -50% maggot meal, MM4- 75% maggot meal and MM5- 100% maggot meal were used for the experiment. The higher the proportion of maggot in the meal, the higher the ether extract and crude fibre. No significant difference (p>0.05) existed between ash content of the experimental diets. Diet MM2 had the best growth performance and highest MGR with a significant difference (p0.05) existed between the growth parameters for diets MM1 MM3 and MM4 A positive correlation (r = 1.0) existed (p<0.05, 0.25) between the growth parameters for the different experimental diets. Highest correlation (r =0.9981) existed p<0.05 between MGR within the treatments. Highest Haematocrit (23%) Haemoglobin content (7.68g/dl) and whole blood clotting time (46 see) were recorded from H. longifilis fed MM5. Without any reservation, inclusion of maggot based meal diet is recommended as feed in the diet of H. longifilis to 75% replacement of fish meal for growth and better healthy condition so as to ensure sustainable aquaculture in Nigeria
