Sicyopterus longifilis de Beaufort 1912

This species is distinguished by the following characters: upper lip with no median cleft, but with a lateral cleft on each side of lip; margin of upper lip between lateral clefts minutely serrated; no tubercle behind median cleft; ridge beneath the upper lip only with feeble papillae; premaxillary teeth tricuspid; first dorsal-fin spines, especially second to fifth spines, are long and filamentous in males; posterior tip of first dorsal fin often exceeding the base of last soft ray of second dorsal fin in males, while the second to fourth spines of first dorsal fin in females are somewhat elongate, but the tip of fin not extending to middle of second dorsal-fin base; membranes notched between spines in female; D I,10; caudal fin with 17-18 (usually 17) segmented rays, including 15-16 branched rays; pectoral fin rays 20-21; scales in longitudinal series 49-57; scales on nape and occipital region considerably smaller than scales on lateral sides of body (Ref. 125665).

Amphidromous. Refers to fishes that regularly migrate between freshwater and the sea (in both directions), but not for the purpose of breeding, as in anadromous and catadromous species. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.Characteristic elements in amphidromy are: reproduction in fresh water, passage to sea by newly hatched larvae, a period of feeding and growing at sea usually a few months long, return to fresh water of well-grown juveniles, a further period of feeding and growing in fresh water, followed by reproduction there (Ref. 82692).

Dorsal spines (total): 7; Dorsal soft rays (total): 10

Lives in coastal streams with moderate to fast flow (Ref. 2847). Usually found in small. clear creeks, often in rainforest within about 50 km of the sea (Ref. 2847).