Species: Gambusia nicaraguensis, Nicaragua Mosquitofish

Gambusia nicaraguensis Gunther, 1866

Nicaragua Mosquitofish

Head and body moderately robust, moderately compressed at rear; head depressed; front nostril not tubular; covering of eye not continuous with skin of head; mouth small, opens at front, slightly oblique, lower jaw slightly projecting, top jaw protractile; jaw teeth consist of an outer row of large backward curved teeth, and several rows of small pointed teeth; 1 dorsal fin with short base, at rear of body, 7-8 (7-9) rays; anal fin origin distinctly before dorsal fin origin in both sexes female with 8-11 rays; pelvic origin well behind pectoral base, near anal fin, tips of fins of males not swollen; pectorals high on flank, 12-14 (usually 13), modified in male, with 5th ray scalloped near its tip; 3rd anal ray unbranched; anal fin modified in male to form an elongate sex organ, that slender, tapering, pointed, with tip curved upwards and with small recurved hooks on its top side, without a fleshy palp; tail base relatively narrow; tail fin rounded branched tail rays 12 (11-14); scales smooth and relatively large, 29-30 (28-31) along side.

Light olive, rows of faint small, dark brown spots on rear of scales in rows along upper body; an oblique dark triangular bar under eye; dorsal fin with 1 row of black spots; tail fin with 1-2 vertical rows of 6-7 black spots, lower margin of tail fin of males bright orange; female with black spot on lower rear of abdomen.

Reaches 5 cm.

High salinity brackish river mouths to marine offshore islands.

Depth: 0-1 m.

Belize to Colombia.

Note: the populations on San Andreas and Providencia Islands likely are a separate species, G. aestiputeus.