Abstract: The effect of heavy metals on Ca2+-ATPase from the sarcoplasmic reticulum in fish muscles has been studied, but there is not any evidence about interaction between heavy metals and Ca2+ in muscle tissue. The concentration of heavy metals (Zn, Cu, Pb) in two economically important fish species (Ctenopharyngodon idella, Hypophthalmichthys molitrix) collected from some ponds in Gilan, Iran were determined using flame atomic absorption spectrometry after digestion methods. Trace metals content in fish samples were 0.88-4.50 μg g-1 for copper, 1.83-5.92 μg g-1 for lead, 5.63-12.63 μg g-1 for zinc and 72.31-173.43 μg g-1 for calcium. There is no interaction between heavy metals and calcium concentration in muscles.