Biochemical costs of a three day long cohabitation in dominant and submissive male Betta splendens

A 3 day long cohabitation in pairs of previously isolated adult male Betta splendens was studied. The first two mornings started with intense fighting, the frequency of which decreased during the day. The bursts of aggression noticed in the mornings were associated with a significant carbohydrate metabolism activation, while daytime activity resulted in a reduction of muscle proteins in the evenings. These changes were more pronounced in submissives than in dominants. The third day marked a shift in the behavior of the pairs: bursts of attack activity were not noticed, while the threatening display frequency increased. During this day a similar reduction in lipids was observed in dominants and submissives. While during the first 2 days the dominant position offered some metabolic advantage, this advantage disappeared during the third day when both members of the dyad seemed to do equally less well than their isolated counterparts. Combined with previous findings obtained in this series of experiments, the present results support the assumption that in this species the presence of one opponent is less well tolerated than the presence of four conspecifics. © 1994 Wiley-Liss, Inc.     

Behavioral tactics control the energy costs of aggression: The example of Macropodus opercularis

Previous experiments on Betta splendens have shown that energy expenditures related to aggression are under social control. The present paper examines the biochemical energetics of social cohabitation in groups of Macropodus opercularis. The species is closely related to Betta splendens, however, dominants use somewhat different behavioral tactics against intruders. In contrast to Bettas, submissive Macropoduses are not harassed by dominants, but are confined to the bottom of the tank. This results in a reduced rate of oxygen consumption in defeated animals (Anabantid fish mainly use atmospheric oxygen). The only metabolic change, compared to isolated controls, is a reduction in hepatic glycogen content. Submissive animals have shifted carbohydrate metabolism towards anaerobic glycolysis. Substantial reductions in muscle proteins, lipids, and glycogen occurred in submissive Betta splendens. Thus, the sharp difference in behavioral strategy results in a sharp difference in the energetic consequences of aggression. A theory is presented regarding the possible role of energetic constraints in the control of behavior. © 1996 Wiley-Liss, Inc.