A studies On Biology Of Some Nile Fish Species (Alestes baremose, Bagrus bayad and Mormyrus caschive)During 98 – 1999

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Neimat Mohammed Abdelrahman, Omer
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Some aspects of primary productivity and biology of Alestes baremose, Bagrus bayad and Mormyrus caschive in Jebel Aulia reservoir were studied. The correlation between some environmental factors and plankton ranged from negative (water temperature and density of plankton, pH and dissolved oxygen) to positive (dissolved oxygen and nitrogen). The correlation between air temperature and water temperature was very highly significant (p< 0.001) and that between air temperature and dissolved oxygen is significant (p<0.05). The food and feeding habits of Alestes baremose, Bagrus bayad and Mormyrus caschive collected from Jebel Aulia reservoir werte studied. Whole guts and stomachs from 363 of A. baremose, 318 of B. bayad and 311 of M. caschive were investigated during June 1998 and May 1999. Alestes baremose is an omnivorous feeder, since it feeds mainly on planktons, insects, seeds, worms, higher vegetation, molluscs and fish remains. Bagrus bayad is a carnivorous feeder, as it feeds mainly on animal sources such as fish, molluscs, insects and shrimp. M. caschive may be considered a bottom feeder, because it feeds on worms, water insects (dragon fly larvae), terrestrial insects and higher vegetation. The relationship between the body weight from one side and the total food weight, stage of gonads maturity and standard length from the other side are very highly significant (p< 0.001) for each species. Sex ratio is close to unity in A. baremose and M. caschive (0.96: 1 and 1.16: 1), but is 1.39: 1 for B. bayad. It is worth pointing out that in all three species males attain maturity stages at a relatively smaller sizes than females. Alestes baremose has two breeding seasons, but Bagrus bayad and Mormyrus caschive have one breeding season. In Alestes baremose the length of first maturity ranged between 50.7 to 14.1 cm in total length. Bagrus bayad 22.5 to 35.1cm. In Motmyrus caschive the first length of maturity is very difficult because their stage one is not found in all collected fishes
studies, Biology,Nile,Fish,Species