Spectrolebias costai was described in 1990 as Cynolebias costai and moved in Simpsonichthys later. In the end of 2011 it was placed in the genus Spectrolebias. The description was dated in 1990 but actually published in February 1991 (source: Killi Data Online).

The British aquarist Paul Baker however published an accurate description (also in 1990) of the species with drawing but.... without any diagnosis and named the species Cynolebias costae. As International Nomenclature rules say that a diagnosis must be part of the description it was rejected as valid and the Lazara paper was accepted.

The name was given to honor Mr. Luis Costa (and not assigned to Dr. Wilson Costa as many, including me, assumed) who discovered the species in April 1982 already. The terra typica was situated in Aruana, Goias State, western Brasil. The distribution is more widely and S. costai can be found in Parc nacional do Araguaia, Tocantins, Brasil.

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. Since the end of 2011 Costa has changed the status from Spectrolebias from subgenus to genus again.

To breed these species one must be an experienced Killi enthusiast and especially the preservation of the eggs is a tricky issue. Also the breeding of the tiny youngsters when they are just out of the egg is a challenge and will only succeed with tiny food like Paramecium and micro nematodes. Only after a few weeks will the joung be able to eat newly hatched Artemia nauplii. It is not only a challenge to obtain the two species mentioned above but also to propagate them properly. The species within Spectrolebias have varying development times with large differences in the time it takes for the eggs to fully develop. But in general it takes longer than with many other species that deposit their eggs in the soil. It is therefore important to regularly check the peat in which the eggs are deposited and stored after a period of 3 months on their development status.

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 Spectrolebias 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 6-8 weeks the fishes are capable to produce there first eggs if various types of small living food was given sufficiently and water was canged on a regular basis.

Remarks:

Max. size 4.0 cm.
Dorsal 21.0,
Anal 24.0,
D/A 3.0,
LL scale count (average)25.0
Pre- dorsal length to % SL – 58.0 %
Depth to % SL – 29.0 %

Lazara, K.J. 1991. Cynolebias lacortei, Cynolebias costai and Cynolebias aruana, three new Species of Cloud Fish from Brazil (Teleostei; Cyprinodontiform; Rivulidae). Journ. Amer. Killifish Assoc., 23 (5), (1990): 144, figs. 3, 5.

Costa, W. J. E. M. 2010. Historical biogeography of cynolebiasine annual killifishes inferred from dispersal- vicariance analysis. Journal of Biogeography, 37: 1995-2004.