Spectrolebias semiocellatus was found on 4 April in the year 1996 and originally described as Simpsonichthys semiocellatus. It was discovered by Dalton Nielsen, André Carletto and Andre C. de Luca. The place was close to rio Formoso in the Rio Araguaia basin, Tocantins- state, Western Central Brasil. The species was described as typespecies for a new genus named Spectrolebias.

Spectrolebias was, according to Huber, a subgenus within the genus Simpsonichthys. The species name "semiocellatus", given by the describers, refers to the half ocellus in the posterior border of the anal fin. (semi = half) and (ocellus = eye- like.)

The species is known only from its terra typica but seems to be wide spread following Huber (Killi Data Online) and can be found together with (sympatric) Plesiolebias aruana, Plesiolebias lacerdai, Pituna compacta, Maretecoara lacortei, Simpsonichthys costai and Trigonectes rubromarginatus.

Later, in Costa's revision (2006) of the genera Nematolebias and Simpsonichthys he devaluated the genus status of Spectrolebias to subgenus. In the same work he assigned 4 other species from the Simpsonichthys clan to this subgenus. These species are: S. reticulatus, S. costai, S. chacoensis and S. filamentosus. Since September 2008 another species is added to this subgenus. This was Simpsonichthys inaequipinnatus. Finally the subgenus Spectrolebias was brought to the status of genus again in 2011 also by Costa.

Simpsonichthys semiocellatus is difficult in reproduction and need extra attention during the first days as they need very small food as just hatched artemia or infusoria.

The way they spawn is not as most annual species do, by diving completely into the substratum. They often drop their eggs from above the substratum or direct against it.

Eggs will sink into the substratum afterwards. It is wise to use some coco fibers mixed in the peatmoss that need to be in a thick layer at the bottem.

Best water temperature is between 20 and 28 C. Best storage temperature 25 C. Need storage for about 12 weeks. Eggs are small (1 mm) and have spine like projections.

This species group prefers to live in larger bodies of stagnant water that can be of temporary nature like swamps, flooded land and pools. They can be found in savannah- and forest like areas, mostly on a muddy bottom.

General behaviour is like that from most Simpsonichthys species as they like to dwell in small groups and are not very active in there environment. Not fast swimming but more peacefull standing in shaded places. They eat, as most other annuals do, mosquito larves and small flying insects or crusteans.

After 5-6 weeks the fishes are capable to produce there first eggs if food was given sufficiently.

Remarks :

Max. size 4.0 cm.
Dorsal 16.0,
Anal 24.0,
D/A 8.5,
LL scale count (average)29.5
Pre- dorsal length to % SL – 52.2 %
Depth to % SL – 30.5 %

Costa, W.J.E.M. & D. T.B. Nielsen. 1997. A. new Genus and Species of annual fish (Cyprinodontiformes: Rivulidae) from the Araguaia basin, central Brazil. Ichthyol. Explor. Freshwaters, 7, (3): 259, figs. 1-2.

Costa, W. J. E. M. 2010. Historical biogeography of cynolebiasine annual killifishes inferred from dispersal- vicariance analysis. Journal of Biogeography, 37: 1995-2004. (PDF) Right click to open in new window