Effect of Some Environmental Impacts on Health Condition and Growth Performance of Cultured Oreochromis niloticus at Northern Delta, Egypt.

Abstract

The field study was done to study the effect of both water and soil quality on cultured Oreochromis niloticus (Nile tilapia) in the farms near Northern Delta Lakes. Six earthen ponds (about one Faddan each) were used in this experiment in three different locations; around Edco, Borollus and Manzala lakes. Three treatment-locations were tested in double replicates (2 ponds/lake); so six ponds were stocked with mono-sex males of tilapia (12000 fingerlings/pond with average initial bodyweight of 37±1 g). Growth performance, assessment of heavy metals residues, clinical, postmortem and laboratory examinations were done. The differences in the final weights (harvest) were significant and the lowest body weight came from farms around Lake Manzala and samples of water and soils suffered more from heavy metals pollution and parasitic diseases than fish from farms around Lake Edco and Lake Borollus. Regarding the clinical, postmortem and laboratory examinations; fish suffered from hepatitis, enlargement of the gallbladder, infested with metacercaria of Digenia and larval nematodes in all farms. From this study, overcoming pollution should be done seriously for producing fish fit for human consumption. The result from the study gave important information on the levels of the heavy metals in water and fish tissue .The concentrations of heavy metals in the water and fish tissue were under the permissible limits in Edko and Borollus lakes while in Lake Manzala the concentrations of heavy metals in the water and fish tissue were above the permissible limits. It is recommended that more attention must give to fish resources by the government to continuously reduce to the minimum level of lakes' pollution.