Department Of Marine And Fisheries Sciences University Of Ghana, Legon

ABSTRACT The decreasing availability and increasing cost of fishmeal have called for efforts in evaluating wide varieties of relatively lower cost ingredients that could partially or wholly replace fishmeal. The Black Soldier Fly (BSF), Hermetian illucens larvae hold potential in this regard due to their high protein and fat contents. This study was conducted at the BSF Centre of the Ghana Atomic Energy Commission, Accra, and Aquaculture Research and Development Centre at Akosombo, to evaluate the growth performance of fingerlings of Oreochromis niloticus (Akosombo strain) using diets with BSF larval meal as an alternative source of protein to fishmeal and to determine the apparent digestibility of nutrients of BSF larval meal in comparison to those of traditional sources of protein, such as fishmeal and soybean meal. The BSF larvae were reared on fruit and vegetable wastes and then solar dried. The BSF larval meal was used to replace fishmeal at 25, 50 and 75% inclusion levels in formulated diets for O. niloticus fingerlings. Two other tilapia diets, an on-farm type (ARDEC) and a commercial one (RAANAN), containing 0% BSF larval meal served as controls. In all, five isonitrogenous (380 gkg1 crude protein) and isoenergetic (18 kJg1 gross energy) diets were used in culturing O. niloticus fingerlings (initial mean weight 1.3±0.23 g) for 10 weeks. Apparent digestibility coefficients (ADCs) were determined using chromic oxide as inert marker. The reference diet was formulated to contain 380 gkg1 crude protein and 18 kJg1 gross energy. The reference diet was replaced with test ingredients at 70:30 ratios. Proximate analysis on the whole BSF larvae was found to contain crude protein (37.83%) and crude fat (22.7%) (dry matter basis). All diets were readily accepted by fish. Growth and nutrient utilisation parameters of the cultured O. niloticus fingerlings indicated no significant differences (p > 0.05) among the various dietary treatments. BSF 25 had the highest final mean weight gain (33.82±2.53 g) and the least was BSF 75 (30.53±3.95 g). Whole-body observation of harvested fingerlings xiv showed no abnormalities on the external and internal body. This suggests that BSF larval meal does not exert a negative effect on fish health. Analysis on the cost effectiveness of the various diets used in culturing O. niloticus fingerlings showed that producing a kilogram of fish using BSF 75 diet was more cost effective than other diets. Nutrient digestibility of BSF meal compared favourably with those of fishmeal and soybean meal. The apparent digestibility coefficients (ADCs) of nutrients of BSF meal, fishmeal and soybean meal were high (> 52%), implying good utilization of feed for tissue synthesis and metabolic activities. On the basis of final mean weight gained, feed conversion ratio and the cost-effectiveness of diets, it suggests that BSF larval meal may partially replace fishmeal at best 50% inclusion level without affecting fish growth, health and carcass quality.