Little was known about the early life history of Ariake icefish Salanx ariakensis, listed as an endangered species. We described the morphology of lar-vae, based on wild specimens (5.0-24.0mm BL) collected in the Chikugo estuary, Ariake Bay, in 1998. Yolk-sac and early pre-flexion larvae appeared in freshwater or very low salinity regions [salinity (PSU): 0.0-1.0, water temperature: 10.4-12.6°C] with a larva net, but most larvae of S. ariakensis were collected at brack-ish areas [salinity (psu): 20.5-31.1, water temperature: 12.6-16.2°C] in November and December. They could be distinguished from larvae of the other Salangid species by following diagnostic characters: occurring seasons (fall and winter), pre-anal myomere counts over 50, relative location of dorsal and anal fins (anal fin originates under the 6th dorsal ray), and melanophore patterns on the tail.
