Acute toxicity of copper to sea catfish

Sea catfish (Arius felis) were exposed to aqueous solutions of reagent grade cupric chloride in artificial seawater ($\text{30.0±2.0‰}$, 21–23°C) in four static bioassays. The 24, 48, 72 and 96 h LC₅₀ were calculated and found to be 5.43, 4.17, 3.57 and 2.40 mg l.^?1 copper, respectively. Experimental concentrations of copper producing subtle behavioral changes in this species correspond to less than 0.3% of the 72 h LC₅₀. Based on this comparison with literature values, a new, maximum ‘safe’ concentration for copper in marine waters of 0.01 mg l.^?1 is proposed.