International Journal of Fisheries and Aquatic Studies 2015; 2(3): 166-170 Some aspects of the reproductive biology of Gymnarchus niloticus Cuvier, 1829 (Knifefish) in Lekki Lagoon, Nigeria

Opadokun, Ajani, Opadokun Correspondence, Opadokun, Ajani
Studies were conducted on the gonad morphology, gonadosomatic index (GSI), fecundity and egg size of Gymnarchus niloticus in Lekki lagoon. 420 fish samples comprising of 150 females and 270 males were examined giving a female to male ratio of 1:1.8. Gonad morphology revealed unpaired gonad in both sex. Fecundity ranged "between" 750 to 1291 with a mean of 925.61 ± 106.90SD and it correlated significantly (P<0.05) with gonad weight (r=0.63) and standard length (r=0.64). Mean oocyte diameter was
more » ... .41 ± 1.29 mm and it had significant relationship (P<0.05) with total weight (TW), gonad weight (GW) and maturity stage (MS). Fully matured gonads were observed from May to July and November to January while spent gonads were found in August and September. Mean GSI were 1.928 ± 0.304SD and 0.007 ± 0.164SD in female and male respectively. G. niloticus in Lekki Lagoon exhibited gonochoristic reproductive strategies having low fecundity but large ova with iteroparous life history.