Reproductive biology of Tilapia zillii (gerv, 1848) from Abu Qir Bay, Egypt | بيولوجية التكاثر لأسماك البلطى الاخضر من خليج ابو قير، مصر

Reproductive aspects in addition to condition factor and hepatosomatic index were analyzed for Cichlid: Tilapia zillii collected from the beach-seiners operating in Abu Qir Bay during the period from June 2000 to February 2001. The overall sex ratio (M/F) was 1: 1.05. Length at first sexual maturity was 8.7 cm for females and 9.7 cm for males. Gonadosomatic index revealed that spawning season lasted from June to September with peak in July. Macroscopic examination for the gonads of T. zillii indicated that adult females had 4 stages of gonadal development (matureII; vitellogenic stage III; ripe stage IV and spent V). The maturity stages of males were three (matureII, mature III, and ripe stage). The microscopic features of gonadal sections of both females and males showed that T. zillii gonads developed like other tilapian fishes inspite of their hyper saline habitat. Ripe females released in the average about 2138 eggs per cm of length and 2464 eggs per gm of gutted body weight. Condition factor showed similar trend between both sexes of increase and decrease. Hepatosomatic index in females attained higher values over males.

National Institute of Oceanography and Fisheries (NIOF), Egypt

The Chief Editor: Prof. Fatma Aly Abd El-Razek E-mail: [email protected] The Egyptian Journal of Aquatic Research is abstracted in both of Zoological Record and Chemical Abstract since Volume 31(1), 2005.

Published

hepatosomatic index, Tilapia zillii, Abu Qir Bay