# Impacts of Replacing Blended Fish Meal With Diverse Animal and Plant Protein Sources and Their Combinations in the Diets on Growth, Feed Availability, Biochemical Composition, and Blood Chemistry of Rockfish (Sebastes schlegelii)

## TL;DR

This study tested how replacing fish meal in rockfish diets with various animal and plant proteins affects their growth and health.

## Contribution

It identifies a combination of meat meal and corn gluten meal as a viable substitute for fish meal in rockfish diets.

## Key findings

- The control diet with fish meal resulted in the highest growth rate and feed efficiency.
- A combination of meat meal and corn gluten meal maintained growth and feed efficiency without negative effects.
- Most alternative diets reduced growth and feed efficiency compared to the control.

## Abstract

The impacts of replacing diverse animal and plant protein sources, and their combination of fish meal (FM) on growth, feed consumption and utilization, biochemical composition, and blood chemistry of juvenile rockfish (S. schlegelii) were examined. One thousand and eighty juvenile (mean initial weight of 2.5 g) rockfish were assigned to 27 flow-through tanks with a capacity of 250 L each, with 40 fish per tank. Nine isonitrogenous (52.5%) and isolipidic (12.5%) experimental diets were prepared. The control (Con) diet contained 60% FM. In the Con diet, 25% FM protein was substituted with a single protein source of meat meal (MM), chicken by-product meal (CBM), corn gluten meal (CGM), and corn protein concentrate (CPC), as well as the combined MM and CGM, the combined MM and CPC, the combined CBM and CGM, and the combined CBM and CPC, referred to as the MM, CBM, CGM, CPC, CMCG, CMCP, CCCG, and CCCP diets, respectively. Each formulated feed was given to rockfish in triplicate groups and hand-fed twice a day for 12 weeks. Specific growth rate (SGR) of rockfish fed the Con diet was considerably (p < 0.001) greater than that of rockfish fed the MM, CBM, CGM, CPC, CMCP, CCCG, and CCCP diets but not considerably different from that of rockfish fed the CMCG diet. Feed consumption of rockfish was not considerably influenced by dietary treatments. Rockfish fed the Con diet had considerably (p < 0.0001 for both) greater feed efficiency and protein efficiency ratio than rockfish fed all other diets, except for the CMCG diet. However, the experimental feeds had no considerable impacts on the biological indices, biochemical composition except for the sum of the n−3 highly unsaturated fatty acids, plasma, and serum parameters of rockfish. In summary, the combined MM and CGM can substitute 25% FM protein in the diet of rockfish without retardation in SGR, feed availability, and blood chemistry.