The food and feeding habits of two co-occurring marine catfish Galeichthys feliceps and G. ater (Osteichthyes: Ariidae) along the south-east coast of South Africa

The feeding-associated morphological structures of the two Galeichthys species were found to be similar in all respects. Interspecific competition for food was avoided through habitat separation. Habitat preference, as established by dietary analysis and fishing trials, was based on substratum type. Galeichthys feliceps fed over sandy and muddy substrata in marine and estuarine environments, while G. ater fed exclusively over marine reefs. The two species have different caudal fin structures which are probably evolutionary responses to habitat-associated behavioural requirements in the two different environments.
The diets of the two species were investigated and compared using calorific values of prey items. While both species fed predominantly on benthic crustaceans, polychaetes and molluscs, little dietary overlap occurred at the species level. In the estuarine environment, G. feliceps fed mainly on the anomurans Upogebia africana and Calianassa kraussi , crabs Hymenosoma orbiculare and Cleislosoma edwardsii , and several isopod species. In the marine environment G. feliceps fed mainly on two species of crabs, Thaumastoplax spiralis and Goneplax angulata , the echiurid Ochaetostoma capense and the sedentary polychaete Sternaspsis scutata. A high incidence of teleost scales in the diet of G. feliceps juveniles was found to be a consequence of scavenging rather than a lepidophagous habit. Galeichthys ater fed widely on several reef-associated crabs, isopods, polychaetes and cephalopods.