Effects of Pomegranate Punica granatum Juice By-products Supplementation in Diet on Growth Performance, Feed Utilization, Body Composition, Blood Chemistry, and Lysozyme Activity of Juvenile Korean Rockfish Sebastes schlegelii

This study evaluated the effects of dietary supplementation with pomegranate (Punica granatum) juice by-products (PJBP) on growth performance, feed utilization, body composition, blood chemistry, and lysozyme activity of juvenile Korean rockfish (Sebastes schlegelii). Fish with an initial average body weight of 15.2 g were randomly distributed into 50 L rectangular flow-through plastic tanks and fed one of the experimental diets: a control (without PJBP) or diets supplemented with 0.5% and 1.0% PJBP powder, each in triplicate groups. After a 56-day feeding trial, results revealed that dietary PJBP had no significant influence on final body weight, weight gain, specific growth rate, feed consumption, feed efficiency, and survival. Similarly, whole-body proximate composition (moisture, crude protein, crude lipid, and ash) and blood chemistry remained unaffected by PJBP supplementation. In contrast, fish receiving the diet containing 1.0% PJBP exhibited a significantly higher lysozyme activity compared with the control group. Collectively, these findings suggest that PJBP can be incorporated into the diet of juvenile korean rockfish without adverse effects on growth performance, nutrient utilization, and physiological condition, while also enhancing lysozyme activity, and a supplementation level of 1.0% is recommended as optimal.