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Effect of Temperature and Photoperiod on the Reproductive Cycle of
Oreochromis niloticus
Salah G. El-Etreby
Marine Science Department, Faculty of Science Suez Canal University, Ismailia, Egypt.
E-mail: S_eletreby@yahoo.com
Abstract
Monthly samples of Oreochromis niloticus were collected from Fishermen Lagoon, one of Suez Canal side lagoons, in Ismailia. Annual reproductive cycle was determined by following up the monthly changes in maturity changes, gonad index, egg diameters and the histological structures of the ovaries.
Laboratory experiment was done in November - December period, based on the results of the field study, where fishes were out of spawning season and gonads at resting stages. Fishes were exposed to two photoperiods ( 12 h.L. : 12 h.D ) and ( 16 h.L. : 8 h.D.) and four different water temperature ( 16 C, 20 C, 24 C and 28 C ) in glass aquaria.
Fish reared under 16 h.L : 8 h.D photoperiod and 24 C water temperature; all ovaries were in advanced maturity stages with ripe oocytes ready for spawning, while those reared under 28 C, part of them had mature oocytes, the rest show overripening conditions and oocytes in atretic stages.
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The Arab Scientists in Cooperation with The High Institute of Marine Research. Publish all the researches abstracts, which presented in The Regional Workshop on Marine Sciences and Natural Resources, Tishreen University, Lattakia, Syria, 25-26 May 2004.
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The Arab Scientists in Cooperation with The Egyptian Society for Biological Control of Pests . Publish all the researches abstracts, which presented in The First Arab Conference of Applied Biological Pest Control, Cairo, Egypt, 5-7 April 2004.
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Current Status of Plant Protection in Yemen and Future Strategy.
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