Introduction: Uncaria tomentosa, commonly known as cat's claw, is an Amazonian plant with beneficial therapeutic effects on both humans and animals. It is used to treat abscesses, arthritis, asthma, cancer, urinary tract inflammation and prevention of other diseases. Objective: Describe the effect of feeding with Uncaria tomentosa (cat's claw) on Pterophyllum scalare (angelfish) under stress. Methods: A study was conducted of 400 fish with an initial average weight of 0.48 ± 0.01 g and a length of 1.9 ± 0.13 cm. The fish were fed for 150 days with five levels of inclusion of the plant in the diet: 0, 75, 150, 300 and 450 mg of U. tomentosa leaf flour per kg of balanced food and four repetitions in random delineation. Biometrics of the fish were performed every 30 days. At the end of the feeding period the fish were subjected to a 24-hour transport simulation and measurements were taken of their glucose and mortality, as well as the physical and chemical parameters of the water. Results: Significant differences were not found in glucose or water quality parameters between the treatments after simulation of transport for 24 hours. Conclusions: U. tomentosa in the feeding of fish such as angelfish does not cause any antistress effect during transport. Key words: Uncaria tomentosa (cat's claw); Pterophyllum scalare (angelfish); Amazonian plant; ornamental fish; Amazonian fish; phytotherapy; stress.