Stable isotope analyses of carbon and nitrogen are now widely used in food web studies. Stable isotope analysis of fishes is often performed using muscle that require sacrificing animals. Nonlethal sampling provides an alternative way for evaluating isotopic composition for species of concern or individuals of exceptional value. In this research we compared stable carbon and nitrogen isotope values of white muscle with those from scales (nonlethal) in bighead carp (Aristichthy nobilis) and silver carp (Hypophthalmichthys molitrix) from Lake Poyang. Scale derived δ¹³C and δ¹⁵N differed significantly with muscle derived isotope values. Averaged scale δ¹³C value was 2.54‰ higher than muscle, while scale δ¹⁵N value was 0.7‰ lower than muscle. Both fish showed strong linear correlation in δ¹⁵N values between their nonlethal sampled scale and their muscle tissue, support the use of nonlethal sampled tissues for stable isotope analyses of fish. Strong correlation in δ¹³C only found between H. molitrix scale and muscle. Estimating muscle δ¹³C values from scale was not suggest for A. nobilis.