Growth and morphological development of laboratory-reared larval and juvenile Rhinogobius flumineus (Perciformes: Gobiidae)

Morphological development in laboratory-hatched larval and juvenile Rhinogobius flumineus is described. Body lengths (BL) were 5.7 ± 0.1 (mean ± SD) mm just after hatching, reaching 8.9 ± 0.1 mm by day 11, 11.9 ± 0.1 mm by day 24 and 14.7 ± 0.4 mm by day 42. Notochord flexion began before hatching and its flexion was completed on day 1 after hatching (ca. 6.4 mm BL), and yolk completely absorbed by day 9. Body proportions tended to become mostly constant in juvenile stage. Fin-rays of the 2^nd dorsal and caudal fins were present at hatching, and those of other fins appeared almost simultaneously, rapidly increased and attained full complements by 6.8–6.9 mm BL on day 9. Melanophores were few on the body during days 0–3 but increased with growth and covered the entire body surface in juveniles larger than ca. 9.0 mm BL at 11 days after hatching. These features are considered to reflect the ecological differences between R. flumineus as a fluvial species and amphidromous/lentic congeners across the genus.