Effect of Environmental Conditions of Abu-Zabal Lake on Some Biological, Histological and Quality Aspects of Fish

Abstract

3 Abstract: The purpose of this work was to investigate the effect of environmental conditions of Abu-Zabal Lake on fish caught during March, 2005 till February, 2006. The biological, histological and quality aspects were monitored. Species composition; length-weight relation; condition factor; length-scale relation and growth in length of four cichlid species were studied. Also, histopathological alterations for testis and gills of O. niloticus and T. zillii and for muscules of T. sp were recorded. Moreover, physico-chemical, microbial and sensory criteria were evaluated. Results showed that the concentrations of metals in water (Cu, Zn, Cd and Pb) increased during both summer and winter. The most dominant species in this region was O. niloticus (more than 70%) of the total catch, while the lowest was S. galilaeus (4.0%). The best condition factor (K) was recorded for T. zillii (1.94), while the lowest was registered for S. galilaeus (1.74). Also, O. niloticus has the highest growth rate, while T. zillii had the lowest one. T. zillii had the most accumulation of heavy metals in muscles and liver than O. niloticus. Muscles of fish caught during spring and summer seasons were more effected by heavy metals than those during autumn and winter. Although the detected concentration of heavy metals in this study below the permissible levels, however, detectable histological changes in the gills, testis and muscles were observed. On the other hand, both additives used and cooking method were more effective in reduction of metal concentrations. Cooked fish balls (kofta) were suitable for human consumption based on the results obtained.