Early Development of Laboratory-reared Keelback Mullet.

Abstract

The early development, growth, and morphological changes of keelback mullet Liza affinis are described on the basis of a series of reared specimens. Details on the early developmental stages are illustrated, with special reference to morphological transformations and the development of the digestive tract.Artificially fertilized eggs were hatched with 51-56h incubation at 21-23°C. On the 5th day after hatching, larvae completed yolk absorption and started feeding at 3.12±0.06mm TL. Notochord flexion started on the 15th day at 4.08±0.33mm TL. Transformation from the larval to the juvenile stage occurred between 9.14mm and 13.0mm TL, from 25 to 34 days after hatching. Rudimentary pyloric caeca appeared and the formation of the gizzard began when the larvae transformed into juveniles. Between 28.6mm and 40.0mm TL, the formation of the third anal spine took place, then simultaneously, juveniles completed the formation of the adult-like digestive tract. Three marked changes occured in the relative growth at approximately 4-5mm TL, 10-14mm TL and 30-50mm TL. These morphometrical changes were closely related to the notochord flexion and two important developmental changes, i.e. the beginning and ending of the juvenile stage.