Lots of attempts have been done to measure the concentration of mercury in different fish species [1] their muscle [2], liver [3] and gill tissues [4]. Whilst, prior to the present study the concentrations of total mercury (THg) in Liver, white and red muscle tissues had not been compared for Silver Carp (Hypophtahlimichthys molitrix). Silver Carp samples (no. 24) were captured randomly during July to December 2009, from Sanandaj Gheshlagh Dam Lake, using 50 × 3 meters beach seines (mesh size: 5 × 5 cm). Fish samples aged between 2 to 4 years. THg level was measured by Advanced Mercury Analyzer (Leco, Model; 254 AMA) on the dry weight basis. To prevent methyl mercury volatilization, samples were Freeze dried at -54˚C. THg concentration in liver, white and red muscle tissues ranged from 101 – 556, 140 – 780 and 125 – 741 ppb respectively. Our results indicated that the level of THg in liver tissues was lower than THg level in white and red muscle tissues and this might be due to the metabolism of methyl mercury in fish liver [2]. The concentration of THg in white muscle tissue was significantly higher in July in compare with September, October and November samples (P < 0.05). The content of THg in red muscle was significantly higher in August (P > 0.05). As mercury in fish is primarily derives from their food [5], this might be due to the influences of food abundance at which is the highest in summer time in northern hemisphere. THg concentration in liver tissues was significantly lower than the THg level in White and red muscle tissues in October and July respectively (P < 0.05). THg concentrations did not differ between white and red muscle tissue (P > 0.05).
