Survival, growth and sterility of induced triploids in the cyprinid loach Misgurnus anguillicaudatus.

Abstract

Triploids were induced by means of cold shock treatment of eggs after fertilization in the loach Misgurnus anguillicaudatus, to examine their survival, growth and sterility. In eggs fertilized at 26°C and treated at 1°C for one h, 4 and 5 min after fertilization, survival rates at embryonic stage were almost the same as in the untreated controls, although rates of deformed fry were about 12% higher than the control. Fish in these treated groups were 84% triploids. However, lower rates of triploids were found in groups treated more minutes after fertilization. Mean major axes of erythrocytes of triploid individuals were 1.2 to 1.3 times larger than that of diploid controls. Mean body weights of triploids at the end of O-year-oldrearing experiment were small compared with those of the diploids. However, in l-year-old experiment, weights of triploids were greater than those of control. Survival rates of triploids in both O-year-and l-year-old experiments were very similar to those of diploids. Both male and female triploids were entirely sterile.