الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The fresh water catfish, Bagrus species are the most important commercial fish of family Bagridae. B. Bayad is fastly grow and could be reared in artificial fish ponds, they represent a productive source of animal proteins for human consumption. This study is applied on B. Bayad that is the most important economic fish contributing about 9% of the total Nile catch fish and widely distributed through out the Nile River and its tributaries (Bishai and Khalil, 1997).
The present study achieved a comparative study for the reproduction of B. bayad in different habitats, natural habitat (River River) and El-Serw fish farm (captivity), including the morphology, histology, histochemistry of the gonads and pituitary gland with reference to the reproductive cycle.
So, this work aims to clarify the fish cycle, sexual maturity and also to define the main factors affecting on the maturity status of the fish through its annual cycle in different habitats and to explain exactly the spawning period of the fish.
The present study has been achieved for comparative study of Bagrus bayad in different habitats (natural habitat and captivity) for females and males in five directions:
It can be concluded that, in Nile river females of Bagrus bayad, during vitellogenic periods, the hepatosomatic index (HSI) rises as result of synthetic activity of the hepatic cells in which vitellogenin increased with a moderate activity of protein and carbohydrate. However, in fish farms, females have low gonadosomatic index (GSI) and the synthetic activity of the hepatic cells decreased as indicated by low values of hepatosomatic index (HSI) and low content of carbohydrate and protein.
Bagrus bayad failed to spawn in fish farms (captivity) the cause attributed to water quality, i.e stagnant, water and deficient of sexual hormone to complete vitellogenic process. However, in natural habitat (Nile River) a suitable condition of water quality i.e running of current water and other parameters stimulate the brood fish to produce sexual hormones insufficient amount to complete the vitellogenic process.
So, in fish farms the water quality plays an important role in the reproductive cycle and these parameters affect on the synthesis of vitellogenin in the liver cells causing a decline in the ovarian activity as was observed in our study.
In this respect, 17 α- Estradiol is known to stimulate hepatic vitellogenin synthesis as in many other teleosts. In the present study, although a moderate amount of carbohydrate and protein were observed in the hepatic cells, but the ability of fish to spawn was not occurred in fish farm. So, the determination of 17-α estradiol and 17-β estradiol were be taken in our consideration and will be studied in the future.
Also, the extraction of the pituitary gland and other hormones could be used in artificial propagation of the fish. So, the present study is considered as an important step towards the future studies for improving the artificial propagation technique of Bagrus bayad by using induced spawning.