This study aimed to examine the effect of papaya (Carica papaya) leaf extract in feed on the growth performance, feed efficiency, and body nutrient composition of Java barb (Barbonymus gonionotus) at the grow-out stage. The study used a completely randomized design with four treatments and three replicates. The test fish were Java barb at the grow-out stage with an average weight of 50.46±0.35 g fish-1, obtained from the Fish Hatchery Center (BBI) Sawangan, Magelang, Central Java, Indonesia. The test feeds were artificial feeds supplemented with different doses of papaya leaf extract: A (0 g kg-1 feed), B (10 g kg-1 feed), C (20 g kg-1 feed), and D (30 g kg-1 feed). The research parameters included total feed intake (TFI), apparent digestibility coefficient for protein (ADCp), feed utilization efficiency (EFU), feed conversion ratio (FCR), protein efficiency ratio (PER), relative growth rate (RGR), survival rate (SR), and body nutrient composition of Java barb. The results showed that the addition of papaya leaf extract to the feed had a significant effect (p < 0.05) on TFI, ADCp, EFU, FCR, PER, and RGR, but had no significant effect (p > 0.05) on the SR and body nutrient composition of Java barb. The addition of papaya leaf extract at a dose of 30 g kg-1 feed yielded the best results for improving the growth performance and feed efficiency of Java barb at the grow-out stage.
