Utilization of sustainable agri-waste watermelon rind for fishmeal in Labeo rohita diets: Effects on nutritional indices, hemato-biochemical properties, histoarchitechtural traits, amino acid and fatty acid profiles

Abstract

Fish meal (FM) remains an essential protein source with certain limitations like cost and sustainability in the aquaculture industry. Underutilized agricultural wastes with nutraceutical potential could be the feasible solution. This study paved the way for new avenues in the form of economically sustainable low-cost feed for betterment of aquaculture, by evaluating watermelon rind (WMR) as fish meal replacement in diets for Labeo rohita (rohu). Dried water melon rind was incorporated into five isonitrogenous diets (control, 25% fish meal replacement (FMR), 50% FMR, 75% FMR, and 100% FMR then fed to triplicates groups of L. rohita fingerlings. The experiment was conducted for 60 days. There were significant (p<0.05) improvements in nutritional indices of fish fed with 50% FMR. The digestive enzyme analysis showed a promising result in fish fed with 50% FMR diet compared to the control and other experimental diets indicating that fishmeal replaced with 50% FMR diet will be suitable for the digestion in the experimental fish rohu. Finally, histological alterations of organs showed a reduction in the damage of tissues in fish fed with WMR inclusion diets. Enrichment of amino acids (AA) and fatty acids (FA) was observed in the fish muscle. Overall, our results confirm that the 50% fishmeal replacement diet with watermelon rind is a promising alternative for fish meal displaying no adverse effects. Thus, the study concludes that the partial replacement of fishmeal by WMR provides new insights into nutrient utilization, and growth performances, digestibility, and biochemical compositions of freshwater fish L. rohita.