Recycling and repurposing food waste as feed for small-scale zebrafish (Danio rerio) aquaculture

Abstract

Food waste is a globally abundant resource, but currently, it is primarily managed by disposal in landfills, wasting the valuable nutrients. At the same time, commercial fish feeds are expensive and contain unsustainably produced ingredients that are subject to price fluctuations and demand for other uses. Utilizing food waste to supplement or replace traditional feed ingredients could increase the profitability and sustainability of aquaculture, supporting fish species that provide economic, recreational, and ecological value. To explore the feasibility of using food waste in aquaculture, food waste was recycled into "converted fish flakes" (CFF) with a protein ratio appropriate for zebrafish (Danio rerio) in a smallscale aquaculture study. Juvenile zebrafish were fed diets with increasing proportions of food waste (25%, 50%, and 100% CFF) for 32 days and compared to a control group fed with commercial feed. Zebrafish fed CFF diets had high survival rates and growth that was comparable to the commercial feed. CFF diets did not significantly alter zebrafish fecundity or viscerosomatic index (VSI). Histology revealed an increased amount of goblet cells in the intestine and fat deposits in the liver associated with a 50% CFF diet. These results indicate that recycled food waste could be feasibly used in freshwater, small-scale aquaculture of omnivorous fish.