GROWTH RESPONSE AND CARCASS COMPOSITION OF HYBRID (HETERO-CLARIAS) CATFISH FINGERLINGS FED BLENDED INSECT MEALS

This study was carried out to evaluate the growth response, nutrient utilization and body composition of hybrid catfish Hetero-clarias (Clarias gariepinus×Heterobranchus longifilis) fingerlings fed with varying inclusion levels of two blended insect meals (Dung beetle larvae meal (BDM) and Zonocerus variegatus (ZVM) meal) for 70 days. Five isonitrogenous diets were formulated from practical ingredients to contain 40% crude protein and 9.5% lipid with 0-60% inclusion of the two blended insect meals at the same ratio but at different graded levels to replace Clupeid (Sierrathrissa leonensis) fishmeal. The diets were designated as D1 (0%), D2 (5% DBM and 5% ZVM), D3 (10% DBM and 10% ZVM), D4 (20% DBM and 20% ZVM) and D5 (30% DBM and 30% ZVM). Each treatment had three replicates, randomly assigned among 15 net hapas (0.5 m × 0.5 m × 1 m) suspended in three outdoor concrete tanks (8 m×5 m×1.5 m). The concrete tanks were filled to 5/6 of their volume (40 m³) with filtered and dechlorinated tap water, and 20 fish with an initial average weight of 2.55±0.14 g were stocked in each hapa. Water temperature and other water quality parameters were monitored daily and 10 liters of dechlorinated water were added weekly to compensate for evaporation.  Fish were fed 3 times per day at 5% body weight.  

The result showed that fish fed D4 had significantly (P<0.05) greater final body weight (FBW) and percentage weight gain (WG), closely followed by fish fed D3 which was significantly higher than fish fed D5, but not significantly different from those fed D1 and D2 (Fig. 1). There was no significant difference in the percentage of survival among all the fish fed the experimental diets. The total feed in take (TFI), feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) of the fish fed experimental diets followed the same pattern as weight gain, except for fish fed D4 which was significantly higher than all other experimental diets which were similar to each other. The proximate composition results revealed that carcass lipid increased with the proportional increase in the inclusion level of the two blended insect meals in the diet. It could be concluded that 20% proportional inclusion of both the two insect meals improved growth performance and nutrient utilization of hybrid catfish without any adverse effect on their health status, suggesting that the blend of these two insect meals could be a suitable ingredient in the diet of hybrid catfish.