Abstract: There is a change of carapace coloration from cyan to red during growth and gonad development of Procambarus clarkii. The growth, color of carapace and physiological indexes at different growth stages from young to adult crayfish were observed and measured. The results showed that there were remarkable correlations between carapace color transformation and ontogeny and growth speed of crayfish. The carapace color changed from cyan to red, accompanied with the mature gonad,and the gonadosomatic index and liver/body weight ratio increased,the molt cycle was prolonged and the relative growth speed decreased. The growth speed of cyan shell crayfish was significantly higher than that of red shell crayfish. The tests also indicated that environmental factors, such as temperature, light density, directly affected development and maturation of crayfish with the change of carapace coloration.

Key words: Procambarus clarkii, carapace color, growth, gonada development