The age and growth of Tilapia zillii (Gervais) in Opa reservoir, Ile-Ife, Nigeria.

Abstract

Specimens of Tilapia zillii (Gervais) were collected from Opa reservoir in Ile-Ife, Nigeria, between October 1991 and February 1994. The fishing methods employed were castnetting and gillnetting. Annular rings were formed on the scales of 1310 specimens of the species between December and February of each year of study. Male fish specimens grew faster and bigger than the female fish irrespective of age. Fish length at maturity was 11.0cm (male) and 9.7cm (female). Allometric growth was observed in the species and the relationship between fish length and scale length gave a statistically significant correlation r = 0.681; P < 0.001. The species have a good condition factor which ranged between 1.40 to 3.06 with a mean of 2.86 in the reservoir.

Key Words: Tilapia zillii, annular ring, growth, age, condition-factor

Ife Journal of Science Vol.6(1) 2004: 14-18