Black plaice, Pleuronectes obscurus (Herzenstein), were collected and fertilized to observe egg development, temperature-related cleavage rates, and mitotic intervals (${ au}_0$). Fertilized egg was demersal, adhesive, and did not contain oil globules. After 1.75 h, the blastodisc formed, and hatching took place 121 h after fertilization at $14^{circ}C$. The hatched larvae were $3.5{pm}0.16;mm$ in total length. At higher temperatures, eggs developed faster and underwent further identical developmental processes. Additionally, ${ au}_0$ and water temperature were strongly negatively correlated at all temperatures (Y=-2.6981X+98.767, $R^2$=0.9831, where Y is ${ au}_0$, and X is temperature) for black plaice.