The toxicity of cyanide solution to carp increased with a rise in temperature. The result that the concentration of cyanide ion in blood was higher than that in hepatopancreas and spleen，or digestive tract of carp exposed to 10 ppm cyanide ion solution for 5 hours suggested that the ambient cyanide might enter into the blood through the gill. However, the cyanide ion concentration in skin and muscle was higher than that in viscera of carp died in 10 ppm cyanide ion solution. It can therefore be concluded that a large amount of cyanide penetrated into the fish body surface.
Cyanide ion was detectable from carp washed by running tap water for 24 hours after death in 5 ppm cyanide ion solution ， and also from carp exposed to 10 ppm cyanide ion solution for 70 minutes after death of suffocation.