EMBRYONIC, LARVAL AND JUVENILE DEVELOPMENT OF THE ROUGHSKIN SCULPIN, TRACHIDERMUS-FASCIATUS (SCORPAENIFORMES, COTTIDAE)

Embryonic, larval and juvenile development of the catadromous roughski n sculpin, Trachidermus fasciatus, were described using eggs spawned i n an aquarium. The eggs, measuring 1.98-2.21 mm in diameter, were ligh t reddish-yellow and had many oil globules, 0.05-0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3-11.3 degrees C. The ne wly-hatched larvae, measuring 6.9-7.3 mm BL, had a single oil globule, 9-10+25-26=34-36 myomeres and 6 or 7 large stellate melanophores dors ally along the gut. The yolk was almost resorbed, number of pectoral-f in rays attained 16-17, and two parietal, one nuchal and four preoperc ular spines were formed, 5 days after hatching, at 8.2-8.4 mm BL. The oil globule disappeared, and one supracleithral spine was formed, 11 d ays after hatching, at 8.9-9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7-10.3 mm BL. A posttemporal spine was formed 20 days after hatching, at 10.7-10.9 mm BL. The first dorsal fin spines ( VII-VIII), second dorsal fin and anal fin rays (18-19, 16-18, respecti vely) appeared 23 days after hatching, at 12.0-13.7 mm BL. The pelvic fin spine and rays (I, 4) were formed and black bends on the head and sides of the body began to develop 27 days after hatching, at 13.8-15. 8 mm BL. Newly-hatched larvae swam just below the surface in the aquar ia. Preflexion larvae (8.9-9.5 mm BL), in which the oil globule had di sappeared, swam in the middle layer, while juveniles (13.8-15.8 mm BL) began swimming on the bottom of the aquaria. Swimming behavior observ ed in the aquaria suggested that the fish started to change to a demer sal existence at the juvenile stage.