Gonadal Development of Triploid Black Sea Bream, Acanthopagrus schlegeli

Abstract

Triploid black sea bream were induced by cold shock treatment on fertilized eggs. The gonadal development of 2-, 3- and 4-year-old triploid fish were studied histologically during the spawning season. Most of 2-year-old diploid (control) fish were functional males, and about half of the 3-and 4-year-old diploid fish became functional females. The gonad of all triploid fish were male types. GSI value of these triploid fish were lower than those of diploid fish, and histological appearence of the testes indicated that abnormal spermatogenesis was taking place. Some 3- and 4-year-old triploid fish discharged milt when the fish were stripped. These were some spermatozoa with two heads and two or three flagella, and the density of these cells in the milt was very low.