Food habits and trophic resource partitioning among three mormyrid fishes from man-made Lake Ayame, Ivory Coast

Feeding habits and trophic relationships among three mormyrid species (Petrocephalus bovei, Marcusenius ussheri and Marcusenius furcidens) were assessed in the man-made Lake Ayame in Ivory Coast. The index of preponderance combining the occurrence and weight percentages of the identified prey items showed that these three mormyrid species mainly feed on invertebrates, especially aquatic insects. Petrocephalus bovei mainly feeds on chaoborid larvae, whereas both Marcusenius species preferentially feed on chironomid larvae. This segregation of food items associated with the relative abundance of chironomid larvae may reduce interspecific competition between these three fish species, and may therefore allow their coexistence. Horn's food overlap index revealed highly significant similarities in the trophic spectrum between both Marcusenius species, and for the dry as well as the rainy season.