Description:
The mangrove rivulus is an unusual fish that reaches a total length of approximately 2 inches.  The species is hermaphroditic, the only natural example of cloning among vertebrates.  Only males and hermaphrodites are observed in natural populations, however, under laboratory conditions, females have been observed.  Small spots often cover the body, but body color is variable and reflective of habitat type.  Cream or tan colored fishes generally inhabit areas with light bottoms and high turbidity; while those colored brown to maroon tend to inhabit areas with dark bottoms.  Hermaphrodites are identified by a prominent caudal ocellus and a whitish border along the anal fin.

Habitat:
The mangrove rivulus often colonizes marginal or ephemeral habitats and is primarily found in Central and South America.  Florida is the northern limit of this species’ range. In eastern Florida, this species prefers unimpounded, high marsh habitats inside the burrows of the great land crab (Cardisoma guanhumi). In the Everglades and throughout Florida’s west coast, these fish are generally found in stagnant and seasonal pools, as well as in mosquito ditches in mangrove habitats.  Within the IRL, the mangrove rivulus prefers the high marsh above the intertidal zone, areas that are are flooded seasonally, after very high tides, or by heavy rainfall.

Range:  
The mangrove rivulus has the widest range of any member of its family and its range closely parallels that of the red mangrove (Rhizophora mangle). It is distributed from central Florida, through the Bahamas and the Caribbean to southern Brazil.  Florida is the northern limit of this species’ range.