Species: Fundulus persimilis, Yucatan Killifish

Fundulus persimilis Miller, 1955

Yucatan Killifish

Body slender, compressed; head flattened above, with straight to slightly concave upper profile; snout elongate, sharp, about twice eye diameter; cover of eye not continuous with head skin; front nostril not tubular; mouth small, narrow (<27% of head length), distinctly below level of center of eye, opens at front, oblique, top jaw twisted, protrusible, lower jaw projecting; 8 pores under chin; jaws with outer row of pointed conical teeth, inner band of simple teeth; gill rakers short, 6-8; no spines in fins; dorsal fin short based, its origin over anal fin origin in female, slightly before in male, 10 (9-11) rays; anal fin with 3rd fin ray branched, 9 (9-10) rays; pectoral with narrow base, rounded, inserted low on side, 18-19 rays; pelvics inserted well behind pectoral base; tail base slender; tail fin bluntly rounded; small smooth scales, 34-36 midlateral rows; area before eye with scales; lateral line reduced to a series of pits along side of body.

Females with 12-18 narrow dark bars on side, 1st weak. Male with 10-15 narrow dark bars, 1st above pectoral fin base is ½ length of 2nd; fins darker than in female.

Reaches 15 cm (females distinctly larger than males).

Fresh to brackish water, in tidal lagoons.

Depth range: 0-1 m.

A tidal lagoon at Rio Lagartos on the northern Yucatán.