Courtship behaviour was investigated in the sexually monochromatic biparental cichlid, Tilapia mariae, with particular emphasis on the role of submissive behaviour in the process of pair formation. Pair formation successfully occurred when the female had prior residence in the tank, and could occur within a few minutes. Dominant females generally had priority of access to males. In the experiment where pairing occurred, dominant females and males showed practically no overt aggression towards each other. In the confines of a small tank, with no other subordinate conspecifics present, male and female T. mariae did show aggression to one another, but in this case courtship behaviour was entirely absent. Closed-fin postures were employed by both sexes of Tilapia mariae in the early stages of courtship: it is suggested that these served as 'Partner Attack Inhibition' displays. Submissive displays of the kind employed in agonistic encounters are not used in courtship.