Background: Evaluation on the toxicity of two mainly contaminant heavy metals, cadmium (Cd) and lead (Pb) through the food chain was the aim of this study. Methods: A total number of 270 healthy common carp (4±1.14 g) in April, 2015 transported to the Khatam Alanbia University of Technology, Behbahan, Iran. Fishes were divided into three groups and transferred to the 20 L aquaria each containing 30 juveniles. The first group (control) fed by metal-free Artemia fransiscan anauplii throughout the experiment. The second and third groups were feeding by Cd and Pb (1.5 mg/L free ion) contaminated nauplia, respectively. The experimental study was carried out for three weeks and sampling was done in 4th, 7th, 14th and 21st days. Finally, the alterations in plasma biochemical responses were determined. Results: Alanine aminotransferase and aspartate aminotransferase activities increased in response to feeding Pb-contaminated nauplia. Creatine phosphokinase activity showed significant increase in fourth day about both Cd and Pb and at the end of experiment only in Cd treatment (P<0.05). Cholesterol and triglyceride were increased significantly only for Pb (P<0.05). Plasma glucose and creatinine levels increased by both heavy metals compared to the control but glucose just remained high only for Pb at the end of the experiment. Total protein, albumin and globulin were significantly declined in both metal contaminated groups (P<0.05). Conclusion: It seems Pb had a greater toxicity than Cd through the food chain and it may be due to its more trophic transfer than Cd.