الفهرس 
Chapter I : Introduction and Aim of the WorkOnly 14 pages are availabe for public view
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Abstract
Grass carp is considered one of the most important fish cultured all over the world for two reasons, as a cheap source of protein production, especially in developing countries, also used in the biological control of harmful aquatic weeds. In the year 1990, the use of herbicides in combating aquatic plants in the Nile River and irrigation canals were banned. In Egypt, therefore, grass carp were used as a biological control agent for aquatic plants. The most important problems facing fish farming in Egypt are the difficulty in providing seed, since the fish fails in natural spawning, so we need to inject with hormone for artificial spawning. This work aims to clarify the fish sexual maturity cycle, and define the main factors affecting on the maturity status of the fish through its annual cycle and to explain exactly the spawning period of the fish. The hormonal injection experiment was designed to produce artificial spawning. The present study, could define exactly the spawning season of grass carp fish (Ctenopharyngodon idella) and the suitable along period for first sexual maturity of male and female, and also could clarify critical relation between the fecundity and body weight, length and gonadal weight. In conclusion, the studied parameters are considered as very important factors for culturing any fish species. In addition, the present results confirmed the importance of protein and polysaccharide contents in the process of maturation of the female grass carp. Also, the histochemical follow up of the gonadotropic hormone secreting cells confirmed their relation with maturation process of the ovary. Physiological studies show that the possibility of failure for natural spawning of grass carp is due to the decrease of one type of amino acid from the required level. The results of artificial spawning showed the possibility of inducing spawning with an increase in hatching rate. So the present results can stimulate the need for further studies for optimizing the induced spawning technique of the grass carp and improving its commercial applicability.