siamese fighting fish giving birthSimilarly, researchers have found that once pairs of male Siamese combating fish were kept together in a similar tank for a three day period, competitive behaviour was most widespread during the mornings of the first two days of their cohabitation. However, the researchers accompanied that the combating between the two males decreased as the day advanced. The male in the dominant place at the start had metabolic competencies; although as the test progressed, both fish became equal in regards to metabolic benefits. In regards to oxygen intake, one study found that once two male bettas fought, the metabolic rates of both fish didn’t differ before or in the course of the fight. However, the fish who won showed higher oxygen intake during the night following the fight. This shows that aggressive behaviour in the form of combating has long lasting effects on metabolism.