Replacement of Fish Meal With Poultry Viscera Meal in Diets for Juvenile Arapaima gigas: Growth Performance, Hematological Parameters, Fillet Composition, and Gut and Liver Histology

Abstract

This study aimed to evaluate the effects of replacing fish meal with poultry viscera meal (PVM) in diets for juvenile Arapaima gigas, assessing growth performance, hematological parameters, fillet composition, and gut and liver histology. Five isonitrogenous (450.20 g kg⁻¹ crude protein [PRO]) and isocaloric (20.02 MJ kg⁻¹ gross energy) diets were formulated with 0% (0 PVM), 25% (25 PVM), 50% (50 PVM), 75% (75 PVM), and 100% (100 PVM) replacement of fish meal with PVM. A total of 200 juveniles (126.25 ± 3.98 g; 30.74 ± 1.26 cm) were randomly distributed into twenty 500-L tanks (10 fish per tank; n = 4) and fed the experimental diets for 60 days. Survival, feed intake, Fulton’s condition factor, and hepatosomatic, viscera-somatic, and liposomatic indices were not affected by dietary treatments. Weight gain, relative growth rate, PRO conversion rate, and economic conversion rate (ECR) were maximized at 50%–55% fish meal replacement with PVM. Hemoglobin (Hb), hematocrit (Ht), plasma cholesterol (CLS), plasma PRO, fillet lipid content, and fillet ash content increased at higher PVM inclusion levels; however, other hematological parameters, as well as fillet moisture and fillet PRO contents, remained within comparable ranges among treatments. Intestinal hyperplasia and hepatic lipid accumulation were observed in fish fed the 25–50 PVM diets and 25–100 PVM diets, respectively; those changes may represent early physiological responses to dietary composition. Overall, these results indicate that PVM can partially replace fish meal (50%–55%) in diets for juvenile A. gigas during the initial growth-out phase without compromising growth performance or physiological indicators, whereas higher inclusion levels require caution due to growth performance depression and associated nutritional and histological alterations.