siamese fighting fish fin rotIn evaluation, the female fish who were kept isolated didn’t proceed to demonstrate the male standard behaviours after testosterone was discontinued. B. splendens americans were hatched in our laboratory and raised in groups in an enriched atmosphere. At the juvenile or subadult stage, some individuals were relocated to a poor environment and kept in isolation. To compare aggression, a mirror image test was conducted at the juvenile, subadult, and adult stages for each fish, and body parameters in addition to plasma concentrations of 11 ketotestosterone, estradiol, and cortisol were evaluated. Male and female adult bettas raised in a set showed lower levels of aggression than other adult fish.