Nocturnal Mate Recognition and Nest guarding by Female Convict Cichlids (Pisces, Cichlidae: Cichlasoma mgrofasciatum )

This study investigated the ability of nest‐guarding convict cichlid ( Cichlasoma mgrofasciatum ) females to recognize their own mate and to defend their brood effectively against strangers at night. Cichlids in the laboratory bred in nesting boxes made of plexiglas. At the fry stage, various conspecific males were introduced, at night, into the nest box of brood‐guarding females. Female reaction was observed with infrared equipment. If the introduced male was their own mate, females showed little reaction. If the introduced male was a stranger, females reacted by directing head shakes, tail beats, and pushes or bites at the intruder. The frequency of these acts was significantly higher in the presence of strangers than in the presence of mates; the frequency also rose significantly as the size of strangers increased. The two largest classes of strangers fought with the females. These fights included circling behaviour, but not mouth‐locking. Some aspects of female behaviour suggested that mate recognition is based on short‐range chemical cues and not on sound, size, or rapidly diffusing odours. Mate recognition in the nest, at night, is an example of non‐visual communication in fish, and active nest defense at night shows that the convict cichlid, normally considered to be diurnal, can engage in coordinated and effective behaviour in the absence of light.