EARLY DEVELOPMENT OF LABORATORY-REARED KEELBACK MULLET

The early development, growth, and morphological changes of keelback m ullet Liza affinis are described on the basis of a series of reared sp ecimens. Details on the early developmental stages are illustrated, wi th special reference to morphological transformations and the developm ent of the digestive tract. Artificially fertilized eggs were hatched with 51-56 h incubation at 21-23-degrees-C. On the 5th day after hatch ing, larvae completed yolk absorption and started feeding at 3.12 +/-0 .06 mm TL. Notochord flexion started on the 15th day at 4.08 +/- 0.33 mm TL. Transformation from the larval to the juvenile stage occurred b etween 9.14 mm and 13.0 mm TL, from 25 to 34 days after hatching. Rudi mentary pyloric caeca appeared and the formation of the gizzard began when the larvae transformed into juveniles. Between 28.6 mm and 40.0 m m TL, the formation of the third anal spine took place, then simultane ously, juveniles completed the formation of the adult-like digestive t ract. Three marked changes occured in the relative growth at approxima tely 4-5 mm TL, 10-14 mm TL and 30-50 mm TL. These morphometrical chan ges were closely related to the notochord flexion and two important de velopmental changes, i.e. the beginning and ending of the juvenile sta ge.