The dietary habits of the clariid catfish,Heterobranchus bidorsalis(Geoffroy St. Hilaire 1809) in Owena Reservoir, Southwestern Nigeria

The dietary habits of the giant African clariid catfish, Heterobranchus bidorsalis (Geoffroy St. Hilaire 1809) inhabiting Owena Reservoir (Southwestern Nigeria) were investigated. Stomach content analyses established that it had an euryphagous diet. The diet comprised mainly plankton, insects, fish and detritus although, plant parts, benthic invertebrates and tadpoles were consumed. Detritus was very prominent accounting for between 68.1–74.5% occurrence and 13.9–19.6% volume in all sizes of fish examined, which indicated that it was a benthic feeder. There was a progression from planktivorous diet in fish below 12 cm standard length (SL) through a transitional insectivorous phase (SL, 12–27 cm) to a predominantly piscivorous diet in fish above 27 cm SL. It was capable of filter feeding only when young but later became predatory, consuming appropriately sized prey organisms as it grew older. No seasonal variation was established in food preference of any size of fish.