Abstract: Heterologous triploid(3n)Japanese phytophagous crucian carp(Carassius auratus cuvieri T. et S.)were produced by mating heterologous tetraploid(4n)male with diploid(2n)female(Carassius auratus cuvieri).Its main biological characteristics were compared withthat of diploid maternal fish(2n).The triploid has the characteristics of relatively largerbody size, higher body height and caudal peduncle height,more scales above lateral line andbelow lateral line than that of diploid. However,it mantains the herbivorous feeding habit ofdiploid that mainly live on phytoplankton. Male and female were all sterile and have highergrowth rate than that ofdiploid.After cuItured in net cage for 112 days, the body weight oftriploid increased 32.38% than that of diploid. The above results indicate that triploidcrucian carp is a new cuIture object that possesses good prospects.