Effects of Carica papaya seed powder as a plant-based aromatase inhibitor on growth performance, feed utilisation, reproductive health, biochemical indices, and intestinal histomorphology in hybrid red tilapia (Oreochromis spp.)

Plant-derived aromatase inhibitors, such as Carica papaya, are increasingly employed in aquaculture for sex reversal, immunostimulant and growth enhancement. However, their effects on fish physiology, particularly nutrient utilisation, body composition, and serum biochemistry, remain poorly documented, especially in hybrid red tilapia. This study evaluated the effects of dietary inclusions of Carica papaya seed powder (CPSP) at dosage levels 0, 30, 60, and 90 g/kg feed on fish physiological parameters. A completely randomised design with three replicates per treatment was used, comprising a 60-day treatment phase and a 90-day recovery phase. During the treatment, higher CPSP (60–90 g/kg) significantly increased weight gain and protein efficiency ratio (PER) (p < 0.05) but impaired feed conversion ratio (FCR) (p < 0.05), with no significant differences in specific growth rate (SGR) (p > 0.05). At the recovery phase, fish previously fed 60–90 g/kg CPSP exhibited significantly improved SGR, FCR, and PER (p < 0.05). Lipid, ash, and moisture content were significantly elevated in fish from the 90 g/kg group (p< 0.05), while carbohydrate markedly declined (p > 0.05). Reproductive metrics showed that 90 g/kg CPSP significantly increased 11-ketotestosterone (p< 0.05) with suppression in oestradiol and GSI (p < 0.05). Serum biochemistry indicated lower aspartate aminotransferase (AST) and alanine aminotransferase (ALT) but higher alkaline phosphatase (ALP), albumin, and globulin in fish from 90 g/kg CPSP groups (p < 0.05). Cholesterol, glucose, and total protein levels markedly improved (p < 0.05). For improved fish health, 60 g/kg CPSP is recommended. Future research should prioritise scalable methods to commercialise papaya seeds as a cost-effective feed additive and sex-reversal agent in aquaculture.