Dietary phytobiotic supplementation enhances growth performance, immunity response, and disease resistance in grouper ( Epinephelus fuscoguttatus ) juveniles

This study examined the effects of a novel phytobiotic-based functional additive (Apex®) supplementation on the growth performance and disease resistance of the brown-marbled grouper. The experimental design consisted of three treatments: a control (0% additive), a medium-dose (0.3%), and a high-dose (0.7%) treatment, all applied over a 90-day period. Each treatment contained 75 fish with an initial weight of 8.3 g, replicated in three hapas. The results showed that supplementation with the additive significantly enhanced weight gain, specific growth rate, total length, and condition factor, as well as improved feed conversion ratio. Additionally, fish receiving dietary Apex® demonstrated reduced prevalence, intensity of ectoparasites, and Vibrio sp. loads, while showing increased levels of red and white blood cells, hematocrit, hemoglobin, lymphocytes, and monocytes. This study highlights the positive effects of novel phytobiotic additives on growth, immune response, and disease resistance in grouper aquaculture, supporting their potential application for sustainable fish farming.