Weight asymmetry and sequential assessment in convict cichlid contests

Abstract

We staged contests between pairs of convict cichlids (Cichlasoma nigrofasciatum) that varied in weight ratio (larger/smaller) from 1.02 to 4.86 to test the predictions of the sequential assessment model. As predicted, contests proceeded in a consistent sequence of behaviour (lateral display, biting, mouth wrestling, and circling), the duration of contests was inversely correlated with weight ratio, and the duration of complete phases of behaviour was independent of weight ratio (a phase is complete if the contest escalates to the next behavioural phase). However, there was temporal overlap in the occurrence of different behaviour patterns and variation in the duration of contests that are not explained by the model. Nevertheless, the structure of convict cichlid contests is consistent with the logic of the sequential assessment model.