Spawning and development of embryo and larva in cultivated Anguilla japonica by artificial induction

In China, studies on the artificial inducement of reproduction in eel （Anguilla japonica） have been carried out since 1973. The silver migrated eel has been previously used as material fish for experiments on artificial inducement. Since the acquisition of wild silver eel has become difficult in recent years, the cultivated eels have been used as our experiment animals. Although the study on the process of the development of the embryo from the wild eel by artificial induction has been reported, the development of the embryo and larva from cultivatedeel has not been published. In this paper, the characters of embryos and early larvae of cultivated eel by artificial induction in every stage were observed and photographs were taken, the whole process of embryonic development lasted for about 49 h at 20.5℃, 39 h at 22.5℃ and 34 h at 24.5℃. The fertilized eggs of the fish are spherical and orange-yellowish, the diameter of swollen egg is 1.0 - 1.2 mm in water. Fertilized eggs were kept in seawater at 22.5 ℃. The first cleavage occurred at 1 h, epiboly began at 11 h, the embryonic body was formed at 28 h and hatching occurred at 39 h after insemination. Newly hatched larva were approximately 3.1 - 3.7 mm （total length） and similar to those of wild eel in terms of external features.