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vol-33REPRODUCTIVE BIOLOGY OF TILAPIA ZILLII (GERV, 1848)
FROM ABU QIR BAY, EGYPT.
EL-SAYED H. KH. AKEL. AND MOHARRAM S. G.
National Institute of Oceanagr & Fish., Alex., Egypt.
Keywords: Reproductive aspects, condition factor, hepatosomatic index, Tilapia zillii, Abu Qir
Bay.
ABSTRACT
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.
