Abstract:
Lack of good-quality and sustainable fish feed is one of the bottlenecks for aquaculture
development in Ethiopia. Therefore, the study aimed to explore the optimal production conditions
in terms of substrate type, feeding rate, feeding frequency, days for maturity, and nutritional
quality of black soldier fly (BSF) larvae using local bio-wastes as potential fish feed in southwest
Ethiopia. The study involved two trials. The first experiment assessed the effects of local feed
ingredients (poultry manure, brewery waste, and rumen liquor) at different feeding rates (100, 150,
200, and 250 g feed/g larvae/day) on BSF larvae biomass production, growth rate, bioconversion
rate, waste reduction efficiency, and days for maturity. The amount of substrate added, total
weight, dry weight, initial and final larval biomass and maturation time was recorded. Then the
recorded data was statistically analyzed using a two-way ANOVA to establish statistical
significance among the groups. Brewery waste was found to be the most effective feed ingredient
at 100 g feed/g larvae/day feeding rates, which resulted in the highest larval biomass production
(12.2 ± 1.03 g), bioconversion rates of 5.19% to 7.89%, and substrate reduction rates of 40.59%
to 46.75%. The second experiment examined the mixed feedstocks with varied feeding regimes
(daily, midweek, weekly, and lump sum). The best performance was observed on a mixture of
poultry manure (Pm) and brewery waste (Bw) with equal proportions (50:50) applied at lump sum
feeding regimes. It produced the highest larval biomass (11.05 g), bioconversion rates of 15.48%
to 22.78%, and waste reduction rates of 30.92% to 36.54%. The proximate composition of larvae
also varied according to the feed ingredient and feeding strategies; the maximum crude protein
(CP) content of 46.5% was shown on larvae reared on poultry manure and brewery waste mixed
in equal proportions (50:50), whereas the lowest CP content of 39.7% was observed on larvae
reared on rumen liquor. The present study paves the way for a more sustainable and localized
approach to fish feed production for aquaculture development in Ethiopia, fostering economic
growth, environmental stewardship, and improved food security.
