Some aspects of the biology of African knifefish, Gymnarchus niloticus (Cuvier, 1829) in Eleyele Lake, Nigeria

Abstract :

Gymnarchus niloticus ranked top among major commercially important species yet to be brought under culture. As a prelude to domesticate G. niloticus, growth pattern, condition factor, feeding habits and nutritive composition of stomach contents of the species in Eleyele Lake was investigated. A total of 85 G. niloticus (28.0 – 2600.0 g weight and 25.0 – 96.5 cm length) were collected monthly for 6 months (May 2018 and October 2018) from fisher’s catch for this study. The length-weight relationship and condition factor were estimated using standard method. Food, feeding habits and proximate compositions of the stomach contents were determined using standard procedures. The results showed that Gymnarchus niloticus exhibited positive allometric growth (3.16) with positive association between length and weight. The mean condition factor was 0.34±0.04. Dietary analysis showed that G. niloticus is carnivorous, feeding mainly on fishes, insect parts and earthworms. The  nutritional composition of stomach contents revealed: Moisture 85.05±1.058–90.12±0.007%; Crude protein 46.73±6.164–56.70±10.759% dry weight; Dry matter 9.89±0.010–14.95±1.058%; Ash 6.59±0.0070–8.26±1.240%; Ether extract 5.65±0.212–7.78±0.704% and Crude fibre (0.01±0.00%). The proximate composition of stomach contents revealed high quality protein and low fibre contents in their feed. This information will be useful in feed formulation for captive rearing.

Keyword :

African knifefish, length-weight relationship, condition factor, food and feeding, nutritive composition, Eleyele Lake

Author(s) : Olanrewaju, A. N., Kareem, O. K.
Downloads : 5
Published Issue : 2022 Vol. 17 Number 1

2022 Vol. 17 Number 1