The experiment was conducted to evaluate the composition of the hydroalcoholic extract of pitaya bark (Hylocereus guatemalensis) and its effects on the diet of male blue Betta splendens concerning the content of digestive enzymes, liver metabolism, and activity antioxidant. The fish were supplemented with hydroalcoholic extract of pitaya bark (HEPB) at the concentrations of 0.24, 0.45, and 0.90 mg kg −1 of feed for 21 days. The inclusion of 0.24 and 0.45 mg kg −1 HEPB promoted the best results of zootechnical performance. The digestive activity showed an increase in alkaline phosphatase activity only when 0.45 mg kg −1 HEPB. The inclusion of 0.45 and 0.90 mg kg −1 HEPB promoted a decrease in hepatic ALT activity. An increase in CAT activity was observed in the skin of fish fed diets with added HEPB. Conclusion addition of HEPB is benefic for performance and have hepatoprotective.