Abstract – Observations on the biology of Clarias…
A study was made of the biology of Clarias agboyiensis over a period of 32 months in River Anambra basin, Nigeria. The catfish was more abundant in forest floodplain ponds, grassland floodplain ponds and marshes than in rivers (P<0.05). Growth is fast and the recorded size appears to be attained within 2 yr. The parameters of the length–weight relationship and the mean relative condition show that the well-being of females was better than that of males. Mean monthly relative condition ranged from 0.8±0.04–1.40±0.06 with the highest value in May/June and the lowest in August/September. Females matured earlier than males. First spawning took place within the first year of life, and C. agboyiensis participated in communal spawning. The mean number of oocytes per female was 9596±8482 (range 2498–35,720). Of the 42 different food items eaten, insects formed over 61% by number, while fish had the highest food value (>58%) in the diet of all size classes, except the 90–100 mm total length (TL) group. Observed feeding behaviours were foraging, shoveling and surface feeding. The helminth parasites were the metacercaria of Euclinostomum clarias, Procamallanus laevichonchus, a larval spiruroid (f. Physalopteridae) and an unidentified acanthocephalan. C. agboyiensis constitutes a new host for these parasites. The encystment of the metacercariae of E. clarias in the kidney, liver and ovary of C. agboyiensis is reported for the first time. In the light of these observations, some management strategies were formulated with the help of the fishing communities and are now being implemented on a local basis.
Fisheries Research 06/1998; 36(1-36):47-60. DOI:10.1016/S0165-7836(98)00078-2