Evidence brief: Emerging insect-based aquafeed for sustainable African catfish production

Abstract

The current study assessed the implications of substituting fish meal (FM) with black soldier fly larvae meal (BSFLM) on sustainable African catfish (Clarius gariepinus) production. Five isocaloric experimental diets were formulated and 168-days feeding trials were performed with 1400 improved strains of African catfish. Fish fed with 50% BSFLM expressed the lowest and highest feed conversion ratio, and daily weight gain and specific growth rate. Fillets from fish fed diet with 50 and 75% BSFLM inclusion expressed higher lauric (11.4–16.7%) and linoleic acids. Omega-6 fatty acid was 19-fold higher in fillets from fish fed diet with 75%BSFLM. There was 5–8% and 9–11% higher crude protein in fillet from fish fed diet with 50 and 75% BSFLM, respectively. Essential amino acids in the fillets, particularly lysine [11 – 18g/kg] and methionine [11 – 27g/kg] values were significantly higher in catfish fed diet with BSFLM diets than with FM. Diet integrated with 50% BSFLM showed the best return on investment (105.2%) and cost-benefit ratio (1.05). Integration of 50–75% BSFLM into African catfish diet offers a sustainable and cost-effective alternative to conventional fish feed, with promising long-term nutritional and health benefits for the aquaculture industry.

Introduction

The current spiralling of the world human populace is leading to a heightened rate of animal protein consumption, with a particular emphasis on fish [1,2]. The rising demand for protein underscores the importance of exploring alternative sources of animal protein, such as insect meals, particularly black soldier fly larvae meal (BSFLM). This exploration, in turn, contributes to increased fish production and a concomitant reduction in production costs to satisfy the escalating demand for animal sourced proteins [2,3]. Furthermore, adoption of insect meals has been reported to reduce overreliance on fishmeal (FM), the aquacultural primary sources of protein [4,5] chiefly sourced from seas, oceans, and inland waterways, which have often been prohibitively costly, leading to expensive fish feeds. Additionally, the need to sustainably utilize marine resources and reduce human-livestock food-feed competition necessitates a rethink on alternative animal protein sources [6–8].

Black soldier fly larvae (BSFL) can be mass-produced cheaply from various organic substrates [9]. In addition, their ability to degrade organic waste has the potential for use in waste management [10,11], resulting in a protein-rich product that can be processed into a meal for use by livestock [12,13]. The BSFLM has satisfactorily been embraced in multiple studies as a principal source of protein in poultry, swine, and other species of livestock with encouraging results [14–20]. Furthermore, dietary formulations containing BSFLM have undergone evaluation across diverse species of fish, encompassing channel catfish [21], Nile tilapia [22–24], rainbow trout [25–29], pikeperch [30], turbot [31], hybrid tilapia [32] and Atlantic salmon [33–36]. These investigations consistently indicate that BSFLM can partially substitute FM in fish diets, without impairing health indices and growth performances. Zhou et al. [37] and Li et al. [38] documented that the incorporation of BSFLM did not yield detrimental effects on the health, quality parameters of carcass, biological characteristics, and growth of Jian carp (Cyprinus carpio var. Jian). In addition, Stamer et al. [39] noted better performance in rainbow trout reared on BSFLM-based diets compared to those fed on fishmeal-based diets. Xiao et al. [40] also reported favorable results while utilizing BSFLM in raising the yellow catfish (Pelteobagrus fulvidraco). Zebrafish (Danio rerio) partially reared on BSFL meal exhibited no adverse impact on gut and histomorphology indices and may potentiate the growth factor genes [41].