Stages of embryonic development of the ice goby (shiro-uo), Leucopsarion petersii

A series of normal stages for the embryonic development of the ice goby (sh iro-uo), Leucopsarion petersii, which belongs to the Perciformes, is descri bed. Stages are based on morphological features, by utilizing the optical t ransparency of live embryos from the first cleavage to the hatching stage. Fertilized eggs were obtained by artificial insemination and normal embryog enesis was accomplished in a defined medium in plastic petri dishes at 19 d egrees C. Shiro-uo eggs were surrounded by a very thin and clear chorion an d could be dechorionated with forceps very easily. Developmental stages wer e mostly comparable to those of other fish embryos described so far, but se veral differences were indicated, such as the third cleavage plane being ho rizontal, and that the length of the cleavage cycle increased gradually fro m the very early stages. Also, there were differences in the relative rates of organogenesis of the brain, eyes, otic vesicles, and somites when compa red to the zebrafish and medaka.