Replacing fish meal by Chlorella sp. meal: Effects on zebrafish growth, reproductive performance, biochemical parameters and digestive enzymes

Protein-rich microalgae are a potential alternative to fishmeal in aquaculture. In this context, this study evaluated the effects of fish meal (FM) replacement by Chlorella sp. meal (CM) on the growth performance, biochemical parameters, enzymatic activity and reproductive performance of zebrafish (Danio rerio). Six experimental diets were formulated to progressively replace FM. Up to 100% of FM was replaced with CM content at 0, 10, 20, 30, 40 and 50 g/kg diet. A total of 450 zebrafish were randomly divided into six groups, each group containing five replicates with 15 animals per replicate. After 60 days of feeding trials, animals fed 40 g/kg CM showed significantly better growth compared to animals fed diets with no CM. Likewise, animals fed 50 g/kg of CM presented the lowest levels of total cholesterol, LDL and triglycerides. The inclusion of CM had no significant effects on enzymatic amylase and lipase activity, while significantly increasing alkaline phosphatase activity. The highest levels of Chlorella sp. meal in the diets (40 and 50 g/kg of CM) provided the highest egg production (P = .004), hatching rate (P = .004) and larval survival (P = .009) at 6 days post-fertilization. The replacement of FM by CM generated an increase in the final weight, accompanied by an improvement in total cholesterol, LDL, triglyceride levels, in addition to improving the reproductive performance of zebrafish, proving to be an interesting alternative to FM in zebrafish juvenile diets.