Studies on the behaviour of cyprinodont fish. III. The temporal patterning of aggression in Aphyosemion striatum (Boulenger).

The fighting behaviour of Aphyosemion striatum is described. Particular attention was paid to the changes that occurred in the pattern of aggression during the course of an encounter. It was shown that the tempo of fights increased, that is, as the fight progressed the number of elements of behaviour per unit time increased. The three most frequent elements were Quivering, Tail Beating and Attacking and it was shown that they succeeded each other, in maximum frequency of expression, in the order given above, throughout a fight. Fin Clamp, occurring at the beginning of fights and, in losers, at the very end, signalled unwillingness to fight. Almost all the elements alternated with Full Display which was indicative of arousal. The increasing level of aggression followed by sudden defeat of one fish could be accounted for in terms of a positive feedback interaction between participants followed by overloading in one animal. A major prediction of this model is that progressive matching in levels of aggression will occur during a fight and this was shown to happen. An adaptive reason for this pattern of aggressive behaviour is proposed, which is that it can minimise the effects of factors unrelated to reproductive fitness in deciding the final outcome of a fight.