Described as Rivulus ocellatus. Placed in Kryptolebias by Costa in 2006. This species was many years seen as a synonyme to Kryptolebias (Rivulus) marmoratus. Now re-described as a taxon for it's own with the name Kryptolebias hermaphroditus, Costa 2011. The name Kryptolebias ocellatus is now designated to a species formerly described as K. (Rivulus) caudomarginatus (Seegers 1984). The latter name is not valid anymore.

The genus Kryptolebias was also erected by Costa, first named Cryptolebias. This name however was occupied by a fossile species and Costa had to change it in a later publication. Kryptolebias ocellatus and K. marmoratus were described originally within the genus Rivulus.

Abstract : Taxonomy of Kryptolebias ocellatus (Hensel) and K. caudomarginatus (Seegers) has been poorly defined and mostly based on a few specimens bred in aquaria. They were considered as valid species and are redescribed based on recent collections in the type locality area, the mangroves of Rio de Janeiro state, south-eastern Brazil. Both species are considered closely related to K. marmoratus (Poey), with which they share the presence of four neuromasts on the posterior supraorbital series, a long anterior nostril, and a bony laminar ventral process on the fifth ceratobranchial; K. ocellatus is distinguished by an unique colour pattern in the hermaphrodite, more slender caudal peduncle, and a shorter pelvic fin, and K. caudomarginatus by possessing more vomerine teeth, longer dorsal fin base, and a unique male colour pattern. The type locality of K. caudomarginatus is corrected.

Source: Killi Data Online, J.H. Huber 2006.

Costa 2011. The study of morphological characters of the holotype of Rivulus ocellatus (= Kryptolebias ocellatus) revealed that K. caudomarginatus (Seegers) is a synonym of K. ocellatus. The species identified until now as K. ocellatus is redescribed as K. hermaphroditus, which is distinguished from all other species of the K. marmoratus group, which also includes K. ocellatus and K. marmoratus, by having a unique colour pattern. Available molecular data support K. hermaphroditus as a distinct species, more closely related to K. marmoratus than to other congeners.

Kryptolebias hermaphroditus is only known from the coastal plains of south-eastern Brazil, in the states of Rio de Janeiro and São Paulo, and comprises only hermaphroditic individuals.  

Kryptolebias hermafroditus, found in the South East of Brasil, is very close related to Kryptolebias marmoratus ( as stated above) that lives more northerly along the east coast of South- and Middle America and on the islands of the Caribbean archipel as high as The Key's of Florida, USA. Both species are hermafrodite fishes. This means the species is able to self-vertilisation. It is subject to major study (Harrington, B. Turner) and both are unique in their behaviour within the whole superfamily Rivulinae as they are the only hermafrodites. Costa 2011 staes that K. hermafroditus shows solely hermafrodit behaviour. K. marmoratus also uses primaire males so now and then in the breeding. The species occurs mainly in brackish and marine environments but is reported also in coastal area's with fresh water.

Breeding is easy but adding some salt in the breeding tank is wise, especially if the species is just imported or fully adult. Eggs are rather big, almost 2 mm in diameter and need about 14 - 20 days to develop. The female does not need a male for fertilisation so breeding is possible with a single fish.

Kryptolebias hermaphroditus is mostly seen in pure marine water as in mangrove areas where they live in abandoned crabholes and shallow ajectant pools for their protection against predation.

Max. size 7.5 cm.
Dorsal 8.5,
Anal 11.5,
D/A 0.0,
LL scale count (average)47.5
Pre- dorsal length to % SL – 75.3 %
Depth to % SL – 18.6 %

Hensel, R. 1868. Beitrage zur Kenntniss der Wirbeltiere Sudbrasiliens. Archiv. Naturgeschichte Wiegmann, 34: 365.

Costa, Wilson J. E. M.: 2011. Identity of Rivulus ocellatus and a new name for a hermaphroditic species of Kryptolebias from south-eastern Brazil (Cyprinodontiformes: Rivulidae) Ichthyological Exploration of Freshwaters-Volume 22 Number 2