Muscle metabolic changes during the first six hours of cohabitation in pairs of male Betta splendens.

Muscle metabolic effects of aggression were investigated during the first 6 hours of dyadic contests in male Betta splendens. In the first 10 minutes the free amino acid content of the carcass was reduced. At the end of the fight (after 30 minutes) a significant reduction in glycogen content and an increase in free glucose were noticed while amino acids were still reduced. The reduction in glycogen was more intense, while the increase in free glucose was smaller in losers. These modifications disappeared after 360 minutes, but at this time a significant reduction of protein content (both in winners and losers) and an increase of amino acids in winners were noticed.