Early development of squamation for Oplegnathus fasciatus

This paper studies the scale formation at early developmental stages of Oplegnathus fasciatus by using Alizarin red staining method. The fish have three scale starting centers, including the posterior margin of gill cover, above side of lateral line and the caudal peduncle. At rearing water temperatures of 24～27 ℃, primary scales appeared first in these three starting centers at 20th day. Scales originated from back edge of operculum to pectoral fin base toward upward and downward as well as before and after expansion; scales originated above lateral line on back edge of pectoral fin expanded downward and forward and backward, and those originated from caudal peduncle in front and rear extension. The scales on the top of head extended to periphery. At 40 th day, the whole body surface was covered by scales, coming into young fish stage. The development of scales extending to lower area of the body surface was faster than that in the upper area surface, and extension in upper and lower direction was faster than that to direction before and after. Expansion paused after extending to the operculum, backward to the end of caudal peduncle, and the last part of scales coverage was operculum. Scales of O.fasciatus belonged to ctenoid scale type with smaller size. The sizes of scales were very different in the same area at the same developmental stage. Ridge number on primary scale in relation to developmental stages of O.fasciatus could be expressed by quadratic equation.