Species: Kryptolebias marmoratus, Mangrove Rivulus

Kryptolebias marmoratus (Poey, 1880)

Mangrove Rivulus

Body elongate, cylindrical; head flattened; sensory system on top of head with grooves and exposed pads rather than pores; covering of eye partly continuous with skin of head; mouth slightly upturned, at front, short, not reaching under eye, top jaw extendible; teeth small, weak, conical; front nostril in a forward projecting tube that extends beyond front profile of head, rear nostril a small slit before and above eye; 9 lower gill rakers; fins without spines, although 1st ray may be unbranched; dorsal fin at rear of body, its origin over base of last few anal rays; dorsal fin 8-11, edge rounded; anal fin 10-13, edge rounded; pelvics on abdomen, at rear, 6 rays; pectorals rounded, on mid-side, 13; tail fin rounded, 30-31 rays; body with smooth scales, 47-51 along side; lateral line reduced to sensory pits along side of body; fertilization internal, with eggs then being laid.

Light to dark brown, with irregularly arranged dark spots forming a checkerboard pattern along upper side and all of tail base; a dark spot on side just above base of pectoral fin. Hermaphrodite: with a row of silver to gold spots along flank; a large dark cream ringed ocellus a little below the top of the tail fin base; Male: with a orangish cast to side of body and fins, upper and lower margins of tail fin not distinctly colored.

Reaches 6 cm.

Lives in shallow mangrove lagoons and hypersaline ponds; emerges from the water and can occur in abundance in burrows made by insects in red mangrove logs.

Depth range: 0-2 m.

Florida to Brazil.