Sustainable aquaculture leveraging black soldier fly larvae meal for economic and ecological gains in small-scale frog farming

Abstract

The common lowland frog (Hoplobatrachus rugulosus) is an economically important species in Southeast Asia, with increasing demand for consumption. However, natural frog populations are rapidly declining, while production from farms is insufficient to meet market demand. Frog feeds are also costly, prompting interest in the use of black soldier fly (BSF, Hermetia illucens L.) as a promising alternative protein source. BSF is highly nutritious and can be produced using household waste. This study aimed to determine the optimal inclusion level of BSF larvae (0%, 30%, 50%, 70%, and 100%) in the diet of common lowland frogs, focusing on growth performance, feed conversion ratio (FCR), survival, and production cost. Froglets (n = 100; 20.50±0.05 g) were stocked in triplicate plastic ponds and fed daily at 5% of their body weight for 120 days. The results showed that growth parameters, including average weight gain, specific growth rate, average daily weight gain, and FCR, were significantly better in froglets fed diets with 100% and 70% BSFL inclusions compared to lower inclusion levels. Survival rates were also higher with 70% and 100% BSFL inclusions, though not statistically significant compared to other treatments. Additionally, diets with 100% and 70% BSFL inclusions were more cost-effective than diets consisting entirely of commercial feed pellets. These findings demonstrate that BSFL is a highly promising alternative protein source for replacing commercial feeds in frog diets, with up to 100% inclusion having no adverse effects on growth performance or survival.