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The food and feeding habits of the African catfish, Clarias gariepinus (Burchell, 1822) (Pisces: Clariidae) in Lake Hawassa and Shallo Swamp, Ethiopia
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A total of 525 catfish samples were collected with various fishing equipment, including hooks, longlines, and different mesh sizes of gillnets (4–12 cm). Out of these specimens, 379 (72.2%) stomachs contained prey items, whereas 146 (27.8%) were empty stomachs. Overall, fish prey, zooplankton, detritus and phytoplankton were the four most important food items, accounting for 48.1%, 21.8%, 17.1% and 5.9% of C. gariepinus diets by volume respectively. Diet composition varied across different size classes of the fish. The smallest fish (<37 cm standard length) mainly consumed detritus, mud (sediment), and zooplankton which comprise 41.2%, 29.3%, and 19.8% of the total volume, respectively. The larger fish (>37 cm SL) primarily fed on fish prey (14.0–74.1%) followed by zooplankton (11.2–21.3%) by volume. The relative importance of detritus, mud, zooplankton, phytoplankton, and insects decreased with increasing fish size from the Ribb Reservoir. The food and feeding habits of C. gariepinus significantly differed between dry and wet seasons. Fish prey and detritus were mainly consumed in the dry season and contributed to 63.6% and 21.9% of the total volume respectively. Zooplankton and phytoplankton were the most preferred food items during the wet season, contributing 71.8% and 22.2% of the total volume. Generally, C. gariepinus appears to be an omnivore, the species exhibits ontogenetic dietary shifts with larger specimens being more carnivorous, and the species exhibits dietary plasticity across wet and dry seasons, which may be linked to food availability from the Ribb Reservoir.
Abstract: Natural food items of catfish (Clarias gariepinus Burchell, 1822) were investigated in the River Asi from September 1996
to October 1998. Analyses of stomach contents showed that the catfish feed basically on Arthropoda, mostly Diptera larvae, and on
plant materials to a considerable extent. A successful filter feeding was observed, especially during the summer period
The feeding habit of the African catfish Clarias gariepinus (Burchell) was studied by assessing the stomach contents of 419 (287 juveniles- 17.1- 44.7 cm TL and 132 adults- 55.2- 109.0 cm TL) collected between February 2003 and January 2004 in Lake Chamo. Different kinds food items were found in the stomachs such as zooplankton, insects, fish scales, fish and detritus. Zooplankton occurred in 75.4% of the stomachs and accounted for 83.1% of the total volume of food consumed. Detritus occurred in 33.7% of the stomachs and contributed 10.9% of the total volume of food items. Fish (O. niloticus)occurred in 15.5% of the stomachs and accounted for 4.2% of the total volume of food organisms. Fish scales were found in 20.5% of the stomachs and contributed 1.2% of the total volume of food items. Insects occurred in 27.2% of the stomachs but their volumetric contribution was relatively low accounting for only 0.6% of the total volume. Generally, juvenile fish tended to feed on relatively higher proportion of insects and detritus while adults tended to feed more on zooplankton.
Clarias gariepinus (Burchell) can be stimulated to spawn in aquaria by hormonal treatment and the breeding habits could be observed. After pre-spawning activities such as the raising of dorsal fins and chasing of the female, the male folds around the head of the female and small batches of eggs are laid, followed by some gas bubbles. Eggs are distributed by the female over a wide area. This behaviour agrees with field observations. The final stimulant to spawning under natural conditions is thought to be a substance called petrichor dissolved in flood waters that have run over dry ground.