Replacement of Fish Meal Protein with Giant Worm (Zophobas morio) and Black Cricket (Gryllus bimaculatus) in Diet of Cobia (Rachycentron canadum)

Abstract

Replacement of fish meal with alternative protein ingredients is becoming increasingly important in aquaculture diets. In the present study, giant worm (Zophobas morio) and black cricket (Gryllus bimaculatus) were used to replace fish meal in diets of cobia (Rachycentron canadum). Cobia fingerlings, with average initial weight 80.84±0.65 g, were fed for eight weeks with three diets: basal diet (100% fish meal as the main protein ingredient), 30 % replacement of fish meal with giant worm meal, and 30 % replacement with black cricket meal. The results showed that the apparent digestibility coefficients of dry matter (63.2-69.1 %) and crude protein (83.9-88.1 %) of cobia were not significantly different (p>0.05) among the three diets. No significant difference in growth was observed among treatments (p>0.05); the average final weight of the experimental fish ranged between 113.11±3.67 and 120.01±2.89 g, and average specific growth rate ranged between 0.53±0.06 and 0.61±0.04 %. Similar results were revealed for feed conversion ratio (1.16±0.07-1.21±0.05) and survival rate (100 %), wherein no significant (p>0.05) differences were observed among treatments. Therefore, the present results clearly demonstrate that giant worm meal and black cricket meal can be used to replace fish meal in cobia diets, at least at 30 % replacement.