Author: (Poey, 1880)
FBname: Mangrove rivulus
Comments: Adults inhabit shallow, mud-bottomed ditches, bays, salt marshes and other brackish-water environments; also crab burrows (Ref. 5723), moist leaf litter, decaying mangrove logs (Ref. 93034).  Can withstand heavy pollution of fresh or salty waters and shares its biotope with <i>Poecilia vivipara</i> which is much more abundant (Ref. 35237).  Usually found in water with low oxygen content (Ref. 7251).  Either male or hermaphroditic, females don't seem to exist.  Only about 5% of a population are born as males; after 3-4 years about 60% of the (self-fertilizing) hermaphrodites transform into secondary males by losing female structure and function.  The proportion of males depends on the environmental temperature.  Below 20°C, majority are males, above 25°C all are hermaphrodites (Ref. 35237).  It is the only known naturally occurring, self-fertilizing vertebrate (Ref. 13056, 35237).  Not a seasonal killifish.  Is very difficult to maintain in aquarium (Ref. 27139).