Influence of Feeding Fish the Dried-Treated Sewage on Physiological Responses and Histological Structure of the Liver

Fish are one of the most extensively distributed organisms in the aquatic environment. A field study was conducted for 102 days at feeding period. A 100 fish/net-Hapa (Nile tilapia, silver carp, common carp and African catfish) were stocked at a rate of 1: 1: 1: 1 using a polyculture system. Two experimental net-Hapa/treatment were used, one treatment as a control fish fed a commercial diet and the second one fish were fed a Dried Sewage Sludge (DSS), product of treating sanitary and agricultural drainage of Al-Reiad city, Kafr El-Sheikh, Egypt). At the end of the experiment, blood samples were withdrawn for measuring the hematological and serum biochemical parameters, also liver samples were taken from each fish species for histopathological examinations. From the obtained results, it was clear that DSS feeding did not negatively affect the blood picture in general, although the significantly elevated values of transaminases activity and triglycerides concentration. The DSS feeding led to some drastic histological alterations in the liver structure. Conclusively, the presence of some pollutants from agricultural and urban drainages whether in the rearing water or in DSS that can negatively affect fish health, production and quality as well as could be inter the food chain and threat human health; so, it is recommended to give more concern on food and water quality (environmental friendly) used in aquaculture to offer more safe products for human consumption.