Common names: needlefish (English), agujón (Espanol)
Strongylura fluviatilis (Regan, 1903)
Body rounded; head length ~ 37% of TL; long cheek (~ 2x length of operculum); eye diameter ~ 32% of length of head behind eye, equal to distance between eyes; snout = 2/3 of head length; no gill rakers; dorsal 15-16 rays, front rays longer, origin over 5th-7th anal ray; anal 16-18 rays, longest rays a little longer than those of dorsal & equal to pectoral; pectoral 21-25% of head length; pelvic origin midway between rear of eye and base of tail fin; tail slightly concave; no keel on tail base; operculum completely scaled, 180-200 scales before dorsal fin.
A silvery stripe along mid-flank, broader at rear; black blotch above base of pectoral.
Size: 45 cm.
Habitat: a freshwater species that also occurs in mangrove areas.
Depth: 0-5 m.
Known from both Pacific and Caribbean drainages; on the Pacific from the Gulf of San Miguel, Panama to Ecuador.