In this study, some metals (aluminium, chromium, copper, iron, manganese, lead, zinc and vanadium) and metalloid (silicon) were determined in water, sediment and some tissues of fish Cyprinus carpio from Mogan Lake. Fish samples were caught in March 2007. As a result of the examination of metals in the water aluminium has the lowest and silicon has the highest concentration. In sediment samples taken from Mogan Lake it was determined that silicon had the highest and lead had the lowest concentrations. Respectively accumulation of metals in gills, muscles and livers was observed to follow the order of Zn > Fe > Si > Al > Mn > Pb > Cr > V, Si > Fe > Zn > Al > Pb > V > Cr > Mn and Fe > Zn > Al > Si > Pb > Mn > V > Cr > Cu.