الفهرس 
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Fish economic importantOnly 14 pages are availabe for public view
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Abstract
In this study, we spotted the light on the effect of design of spawning pond in traditional methods of hatcheries on reproductive performance of O.niloticus ,stress application and increasing of ammonia in water .facilitating the process of collection of fertilized eggs from spawning ponds constantly without separate nor transfer the brood stock to and from conditioning ponds .We based our experiment on creating of new models placed inside the spawning ponds whichever glass or concrete or earthen, with some modifications in the design of spawning ponds and the technique of the application and management procedure , so all that facilitating the process of collection of fertilized eggs from spawning ponds constantly without separate nor transfer the brood stock to and from conditioning ponds. The plan of work consists of 3 experiments each one containing groups of models: - First experiment : Hanging designs in glass ponds: including 2 models. - Second experiment: Hanging designs in concrete ponds:Including 4 models. - Third experiment: (Modified traditional hatchery methods :including 2 models. Experiments was conducted at the period from February to October 2014 so as each experiment lasts 3 months with apparently healthy O. niloticus 42 females with average weights 250 gm ±25 and 21 males with average weights 180 gm ±25. To evaluate the suitability of these models for the hatchery and its efficiency on reproductive performance it was compared with traditional methods in terms of total fecundity, fertilization rate, hatchability rate and number of fry. In addition, plasma cortisol and . un-ionized ammonia in the water. It was noted in the first and second experiments there is no spawning occur in the glass and concrete experimental groups compared with control groups in which have an average reproductive performance for glass control (1305 ,91.7% , 73,9 and 884) and for concrete control(1420 ,92,5%, 72,8% and 957). For third experiment the average of reproductive performance of earthen pond group was (1920, 95,1 % , 75.2 % and 1365 ) and the average number of fry for its control group was (778).The average of reproductive performance of concrete pond group was (1855 ,93.4% , 74% and 1289) and the average number of fry for its control group was(991). By measuring of plasma cortisol in days (0,1,5,15,20) has been observed in the first and second experiments significant increase (230 ng/ml ±25)in control groups after transfer of fish to and from conditioning and spawning ponds and after eggs collection at the end of each spawning period in compared with experimental groups a significant increase was at first day only after transfer fish from conditioning to spawning ponds and the cortisol level was within normal value (16 ng/ml ±5 )during trails of eggs collection because it occurred without the need to capture of females and transfer fish. For plasma cortisol of third experiment it has been observed a significant increase in control groups after transfer of fish to and from conditioning and spawning ponds and after eggs collection at the end of each spawning period in compared with experimental groups a significant increase was at first day only after transfer fish from conditioning to spawning ponds and the cortisol level was moderate value (85 ng/ml ±25 ) after fry collection because it occurred gently without the need to capture and transfer fish. By measuring of un-ionized ammonia in the first and second experiments in days (1,2,3,4,5) of each spawning period the experimental groups was within normal value (0,003 mg/l ±0,001 ) and had showed insignificant increase from day 1 to day 5, but control groups show insignificant increase during days (1, 2,3) and slight increase (0,006 mg/l ±0,002 ) during days(4 , 5). For un-ionized ammonia in third experiment it was measured in days (1,2,3,4,5,10,15) of each spawning period the experimental groups was within normal value (0,003 mg/l ±0,001 ) and had showed insignificant increase from day 1 to day 15, but control groups had showed insignificant increase during days (1 and 2) and slight increase during days (3 , 4 , and 5) and significant increase(concrete 0,16 mg/l ±0, 06 ) and (earthen 0,07 mg/l ±0,06 ) at days (10 and 15). from the above mentioned results, we could conclude the suitability and the efficacy of the third experiment’s design for improving the reproduction performance for O. niloticus.