Effects of Dietary Waste Wet Dates ( <i>Phoenix dactylifera</i> ) on Growth, Feed Utilization, and Health Status of Nile Tilapia, <i>Oreochromis niloticus</i> , and Thin‐Lip Gray Mullet, <i>Liza ramada</i> , in a Polyculture System

In this study, five levels of waste wet dates (WDs) (<i>Phoenix dactylifera</i>) (0%, 5%, 10%, 15%, and 20%) were added to the diets of Nile tilapia (<i>Oreochromis niloticus</i>) and thin-lip gray mullet (<i>Liza ramada</i>) in order to assess their growth, feed performance, whole-body composition, fatty acids (FAs), intestinal enzyme activity, and biochemical blood parameters in a polyculture system. In 15 concrete tanks of 2 m × 5 m × 1 m, five dietary treatments were set up, each in triplicate, with 15 Nile tilapia (10.3 g) and 5 thin-lip gray mullet (5.0 g) fingerlings per tank. The fish were fed a diet that contained ~30% crude protein (CP) for 60 days. The growth and feed utilization of Nile tilapia were all significantly improved by feeding them 10% WD, while thin-lip gray mullet benefited most from feeding 15% WD. According to the blood parameter data, the lowest levels of triglycerides, amylase, and glucose were seen in Nile tilapia fed 10% dietary WD. Furthermore, the 15% WD diet enhanced the polyunsaturated FA (PUFA) profile in mullet flesh. On the other hand, as compared to the other groups, thin-lip gray mullet fed 20% dietary WD had the greatest levels of glucose and amylase.