Passionfruit (Passiflora edulis) Peel Powder Stimulates the Immune and Antioxidant Defense System in Nile Tilapia, Oreochromis niloticus, Cultivated in a Biofloc System

This study aimed to assess the impacts of dietary supplementation with passionfruit (Passiflora edulis) peel powder (PSPP) on the growth, immune response, and expression of immune and antioxidant-related genes in Nile tilapia (Oreochromis niloticus) maintained in a biofloc system. Fish were fed basal diets supplemented with different doses of PSPP at 10 g kg(-1) (PSPP10), 20 g kg(-1) (PSPP20), 40 g kg(-1) (PSPP40), and 80 g kg(-1) (PSPP80). The basal diet, without PSPP-supplementation, was used as a control at 0 g kg(-1) (PSPP0). We observed that the dietary supplementation groups fed different levels of PSPP exhibited no substantial difference or only slight increases in growth performance and immunological response in Nile tilapia (p > 0.05), whereas fish fed diets supplemented with PSPP at concentrations of 10 g kg(-1), 20 g kg(-1), and 40 g kg(-1) had significantly higher mRNA transcripts (approximately 1.5-4.5 fold) of immune (il-1, il-8, and lbp) and antioxidant (gst-alpha, gpx, and gsr) gene expressions than fish in the control treatment group (0 g kg(-1)). These findings suggest that dietary supplementation with PSPP may effectively stimulate the immune and antioxidant defense system and may function as feed additives in Nile tilapia cultured in a biofloc system.