Female mate choice and male parental defense behaviour in the cichlid fish Cichlasoma nigrofasciatum

Female Cichlasoma nigrofasciatum presented with three potential spawning partners of different sizes spawned most often near the medium-sized male. When mate choice was restricted to males of two size classes, females consistently spawned near the larger male. In the former experiment, small males courted females more actively than medium or large males did. This may explain why females occasionally spawned near small males in both experiments. Larger brood-guarding males showed more intensive aggressive behaviour towards an adult conspecific confined near their offspring than did smaller brood-guarding males. Selection will therefore favour the female choice of relatively large mates because such males are likely to be more effective defenders of their offspring.