Effects of replacing dietary black soldier fly larvae (BSFL) meal with fishmeal (FM) in diets for rabbitfish (Siganus sutor) reared in brackish water intertidal earthen ponds

The effects of replacing dietary fishmeal (FM) with black soldier fly larvae (BSFL) meal in rabbitfish (Siganus sutor) diets were evaluated over 90 days in intertidal earthen ponds at Kibokoni, Kilifi Creek. A total of 240 fish were assigned to a completely randomized design with four dietary treatments; each replicated three times. Fish were reared in hapa cages (1 m × 1 m × 1 m) with 1 mm mesh. Four diet treatments were formulated: (T1- 100 % BSFL, T2 – 75 % fish meal and 25 % BSFL, T3 – 50 % fish meal and 50 % BSFL, T4 – control commercial feed. Fish were stocked at a density of 20 fish/m-3 and fed twice daily at 5% of their body weight. The experimental fish had an initial mean weight of 11.64 ± 0.97 g and a mean length of 9.12 ± 0.14 cm. Final mean weight gain of the fish ranged from 22.75 ± 3.89 g in T2 (lowest) to 32.3 ± 4.05 g in T1 (highest). Feed conversion ratio (FCR) did not differ significantly among the diets (P > 0.05), while survival rate (SR) was highest in T2 (93.3 ± 4.73%) and lowest in T1 (71.1 ± 9.18%). The study provides information that will guide farming of rabbitfish in intertidal earthen ponds, and a possible replacement of fish meal with black soldier fly larvae. Further research on optimal stocking densities is strongly recommended.