The abundance and trophic biology of Clarias albopunctatus Nichols & LaMonte, 1953 (Osteichthyes: Clariidae) in a tropical floodriver basin |
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Authors: | Ezenwaji H M G |
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Institution: | (1) Fisheries & Hydrobiology Research Unit, Department of Zoology, University of Nigeria, P.O. Box 3140, Nsukka, Nigeria |
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Abstract: | The abundance, food and feeding biology of Clarias albopunctatus was studied over a period of 17 months in the lower River
Anambra, Nigeria. The catfish was more abundant in late dry season (January–March) and early rainy season (April–June) than
in other periods of the year in the small-sized Akwu pond than in other habitats. Feeding intensity was higher at night and
at dawn (20.00–05.00 h) than during the day (08.00–17.00 h) in the 151–200 mm TL size class and during the rainy season (April–September).
There was no sex-dependent variation in feeding intensity. Insects were the predominant food, followed by crustaceans. Of
primary importance were Chironomidae (mainly Chironomus spp. and Tanypus sp.), Odonata nymphs, Dytiscus sp., mosquito larvae
and pupae, Gyrinus sp., Daphnia sp., Ostracoda and Tilapia fry. Qualitative food composition and food richness were size,
but not sex – or season-dependent. Diet breadth increased with catfish size and during the rainy season. The feeding behaviour
of the catfish include foraging, shovelling and surface feeding. Abundant food and ability to switch to more available items
enable C. albopunctatus to maintain its abundance in the River Anambra.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Clarias albopunctatus abundance food feeding biology River Anambra basin Nigeria |
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