EVALUATING THE EFFECTS OF DIETARY LIPID – CARBOHYDRATE RATIOS ON GROWTH, HEALTH, AND STRESS TOLERANCE OF JUVENILE YELLOW PERCH (PERCA FLAVESCENS)

Abstract

Yellow perch (Perca flavescens) play a crucial role as both a food source and an ecologically significant species in the Midwest region of the United States. However, while wild populations of this fish have declined significantly in recent years, demand for this popular fish has remained high, necessitating their production through aquaculture. Despite their importance in aquaculture, cost-effective feed for yellow perch remains elusive. A common issue observed in yellow perch fed commercial feeds is suboptimal growth, the development of fatty liver and excessive visceral lipid accumulation due to feeding with current commercial feed designed for other species of fish. Addressing this challenge requires a comprehensive understanding of their nutrient requirements. The primary objective of this study was to determine the optimal lipid – starch (L/S) ratio in fish feed and assess its impact on growth performance, health, and stress tolerance in yellow perch. Yellow perch (initial body weight = 8.9 ± 0.3g, n=21) were subjected to five lab test diets, all containing 46 % protein, with varying lipid (11 – 19%) and starch (14 – 22%) levels to produce different L/S ratios (0.5, 0.65 0.83, 1.06, 1.36), and two commonly used commercial diets. A 12-week feeding trial was conducted within an indoor flow-through aquaculture system (21-23°C) with three replicate tanks (20 fish tank-1) for each treatment. The results revealed that fish fed a diet with a L/S ratio of L13/S20, or a ratio of 0.65, achieved the highest growth performance out of the five L/S test diets, based on weight gain (%). Lipid efficiency ratio significantly differed, as the L11/S22 and L13/S20 test diets demonstrated better lipid efficiency than the L17/S16 and L19/S14 diets. Significant differences (P