# Effects of Replacing Fish Meal With Plant Protein Sources in Diets With or Without Jack Mackerel Meal Inclusion on Growth Performance of Red Sea Bream (Pagrus major)

## TL;DR

This study finds that replacing up to 20% of fish meal with corn gluten meal or soy protein concentrate, with or without jack mackerel meal, supports good growth in red sea bream.

## Contribution

The study introduces a method to reduce fish meal in diets while maintaining fish growth using plant proteins and jack mackerel meal.

## Key findings

- Replacing 20% of fish meal with corn gluten meal or soy protein concentrate supports better growth than 40% replacement.
- Adding jack mackerel meal improves growth performance in diets with plant protein replacements.
- The control diet with 60% fish meal outperformed most high-replacement diets in growth metrics.

## Abstract

Due to stagnant production and high cost of fish meal (FM), feed nutritionists are seeking reliable and affordable alternatives. However, low‐FM diets often result in poor palatability, reduced feed consumption (FC), and impaired growth. This study investigates the effects of replacing FM with plant proteins in diets with or without jack mackerel meal (JMM) inclusion on the growth performance of juvenile red sea bream (P. major). A three‐way {2 FM replacement sources (corn gluten meal [CGM] and soy protein concentrate [SPC]) × 2 FM replacement levels (20% and 40%) ×2 JMM inclusion (without and with)} ANOVA experimental design was applied. The control (Con) diet contained 60% FM. In the Con diet, 20% and 40% FM were replaced with CGM and SPC without or with 24% JMM inclusion, named the CGM20, CGM40, SPC20, SPC40, CGM20J, CGM40J, SPC20J, and SPC40J diets, respectively. A total of 675 juvenile fish were assigned into 27 tanks. Weight gain (WG), specific growth rate (SGR), and FC of fish fed the CGM‐replaced diets were significantly higher than those of fish fed the SPC‐replaced diets. Furthermore, dietary replacements of 20% FM achieved significantly higher WG, SGR, and FC in fish compared to those of 40% FM. Additionally, WG, SGR, and FC of fish fed the all‐plant‐protein‐replaced diets with JMM inclusion were significantly higher than those without JMM inclusion. WG, SGR, and FC of fish fed the Con diet were significantly higher than those of fish fed the CGM40, SPC20, SPC40, CGM40J, and SPC40J diets. In conclusion, up to 20% of FM can be replaced by CGM, with or without JMM inclusion, or by SPC with JMM inclusion in a 60% FM‐based diet without significantly impairing the growth performance of red sea bream.