Biology of the Molluscivorous Fish Trematocranus placodon (Pisces: Cichlidae) from Lake Malaŵi

ABSTRACT Tramatocranus placodon is a facultative molluscivore endemic to the Lake Malaŵi catchment basin, Malaŵi, Africa. T. placodon feeds on both Bulinus nyassanus, which is a host of human urinary schistosomes, and Melanoides spp. in the open waters of Lake Malaŵi. We found that there was a dietary shift from insects and small snails to larger snails as the fish grew, and this correlated with the development of the lower pharyngeal bone, which is instrumental in crushing snails. There was also an increase of the proportion B. nyassanus in the diet just before the onset of spawning.