Simpsonichthys parallelus was described by W. Costa in 2000: The type locality is a seasonal swamp in floodplains of rio Formoso, a tributary of rio Correntes, rio Paranaíba drainage, rio Paraná basin, Parque Nacional da Emas, Estado de
Goiás, Brazil. [approximately 22º 45’ S, 42º 00’ W]

Temporary pools in Campo Úmido, in the Cerrado, Brazil.

The name parallelus refers to (from Greek: parallelos, derived in Latin: parallelus), in reference to the parallel longitudinal bands on male dorsal and anal fins.

According to external morphology, parallelus and cholopteryx are strongly related and also related to S. nigromaculatus. The species is Diagnosed by lacking ventral fins like S. boitonei and S. cholopteryx and its dwarf size, like S. cholopteryx, only separated from S. boitonei and S. santanae by the parallel distal outline and margin of dorsal and anal fins and by the pure orange, unmarked, inner caudal fin in males.

The care and breeding of species of the genus Simpsonichthys is for advanced enthusiasts. Propagation is not the only thing that needs extra attention. First, it is not easy to purchase the species because these species are rarely offered. Simpsonichthys are fish that deposit their eggs piece by piece by diving deep into the substrate. They are moderately productive and their eggs generally have an incubation period of 2,5 to 3 months at a storage temperature of 25 to 28 C. However, it is advisable to check at an earlier date for eggs that develop before then. Experience of some breders has shown that eggs are ready to hatch even after 5 to 6 weeks. In some species the developed eggs are very dark in color and therefore it is difficult to see the iris inside the egghull and that makes it difficult to see what state the eggs are in.

Always try out just a few of the eggs before putting all the peat in the water. Such a test is necessary to recognize if the hatchlings will not remain belly sliders and thus will swim well.

It is best to use rainwater because Simpsonichthys is sensitive to calcium-rich water. The best temperature for watering is 18 to 20 degrees Celsius. The young are relatively large when they hatch because their eggs are also quite large. They can eat Artmia immediately after hatching and after a few weeks also much larger live foods such as sieved Daphnia. After 6 weeks the youngsters are already able to produce the first eggs. Their life expectancy in captivity can reach up to 1.5 years. But in nature they do not live long because their pool goes dry after 7 to 8 months.

Remarks:

A breeder I know indicated that breeding Simpsonichthys margaritatus benefited from floating plants above where they come to deposit. This can of course also be the case with the other species of the genus Simpsonichthys.

Max. size 3.0 cm.
Dorsal 17.0,
Anal 21.0,
D/A 2.0,
LL scale count (average)24.5
Pre- dorsal length to % SL – 55.5 %

Costa W.J.E.M. 2000. Descricoes de quatro novas especies de peixes annuais do genero Simpsonichthys (Cyprinodontiformes: Rivulidae) das Bacias dos Rios Sao Francisco e Parana, nordeste e centro do Brasil. Revista Aquarium, 3 (25): 13, figs. 7-8.

Costa, W.J.E.M. 2007. Taxonomic revision of the seasonal South American
killifish genus Simpsonichthys
(Teleostei: Cyprinodontiformes: Aplocheiloidei: Rivulidae) Zootaxa 1669: 1–134.