Spawning habitat and early development of Luciogobius ryukyuensis (Gobiidae)

Abstract

Egg masses of Luciogobius ryukyuensis were found in spawning grounds around the lowest reach of the adult’s habitat in the tidally influenced area of streams on Okinawa Island. The eggs were attached to the underside of stones and were cared for by a solitary male fish. The number of eggs within an egg mass was 191–1368. The eggs were elliptical, measuring 2.0–2.6 mm in length, and 0.6–0.8 mm in width. Early development of L. ryukyuensis was described from laboratory-reared specimens. Newly hatched larvae, measuring 2.8–3.3 mm in body length, had an open mouth, pigmented eyes, pectoral fin buds, an orange-colored yolk sac, and characteristic melanophores along the dorsal and ventral midlines of the body. The yolk was completely absorbed at days 2–3. Notochord flexion began at day 10 and was completed at day 15. The fish started settling on the bottom of the tank at day 34 (14.1 mm in body length) when the body surface started to be covered by intense pigmentation. The eggs and newly hatched larvae of L. ryukyuensis were of standard size of the genus and their morphologies closely resemble those of L. guttatus.