Two different stages of hierarchy formation in Betta splendens were considered. Winners and losers in a short social contact, and dominant and submissive individuals after the establishment of a hierarchy, respectively, were identified. Metabolical determinations (free glucose, glycogen and protein content, glycogen and protein synthesis, glucose and amino acid oxidation, carbohydrate degradation) were performed. Winners and dominant individuals were shown to be able to produce more energy per unit time than losers and submissives, respectively. Differences in energy metabolism between individuals found in different stages of hierarchy formation also occurred: the carbohydrate degradation reached very high values after a short social contact. This is related to the noticed substitution of aggressive encounters with threat displays in the course of cohabitation.