Reproductive aspects of a cichlid fish Tilapia zillii (Gervais) (Pisces: Cichlidae) in Opa reservoir, Ile-Ife, Nigeria

Abstract

A total of 1486 specimen of the fish Tilapia zillii was collected by gillnetting and analysed for aspect of its reproductive biology in Opa reservoir, between October 1991 and February 1994. Sex ratio was approximately 1:1 (male: female). Fish total length at maturity was 15.1cm (males) and 13.2cm (females). The fecundity was 4329 ± 1153.9eggs, n = 685 with an egg diameter of 1.06mm ± 0.67mm, n = 619. The mean gonado-somatic index was 0.39±0.234.1, n = 865 (males) and 1.05±1.011.2, n = 619 (females). The relationship between fish length and fecundity relationship gave a statistically significant correlation (r = 0.5722, P < 0.001, n = 619). The mean relative fecundity was 29.6 eggs per body weight (gm). The species was a substratum brooder and it bred throughout the study period.

Key Words: Fecundity, sex ratio, gonado-somatic index, substratum brooder

Ife Journal of Science Vol.6(2) 2004: 119-122