Abstract: In order to study the tolerance of Carassius auratus for heavy metal (Cu^{2 +}, Zn^{2 +} and Cr^{6 +}), acute toxicity experiments of heavy metal groups with different concentration gradients were designed. The results show that the LC₅₀ of Cu²⁺ solution at 24, 48, 72 h were 2.63, 0.80, 0.73 mg/L, respectively, while SC was 0.022 mg/L. The LC₅₀ of Zn^{2 +} and Cr^{6 +} at 24, 48, 72 and 96 h were 72.74, 59.75, 58.05, 57.80 and 519.05, 391.05, 375.53, 347.03 mg/L, respectively, while SC of Zn^{2 +} and Cr^{6 +} were 12.040 and 66.660 mg/L, respectively. The toxicity of the three heavy metal for Carassius auratus was Cu²⁺>Zn²⁺>Cr⁶⁺.

Key words: Cu²⁺, Zn²⁺, Cr⁶⁺, Carassius auratus, acute toxicity