Alternative name Laimosemion tomasi.

Rivulus tomasi is described from Tobogán da la Selva, a tributary of the middle Rio Orinoco south of Puerto Ayacucho in the Amazonas Territories, southwest Venezuela. It is similar to R. amanapira, R. rectocaudatus, R. tecminae and R. staecki in having a truncate caudal fin, but differs by a
unique combination of character states: tip of pelvic fin reaching between base of 4th and 5th anal fin ray in males, and 39-42 scales in longitudinal series. Rivulus tomasi differs from other Rivulus spp. (except R. amanapira and R. uakti) by unique caudal fin coloration.

Whitin the subgenus Laimosemion this taxon forms a clade (species group) with following components: Rivulus altivelis. R. amanapira, R. rectocaudatus, and R. tecminae.

Rivulus tomasi is named in honor of
the German aquarist, adventurer and fish collector Joachim Tomas who was one of the co-collectors of the species during a survey in 2010. Joachim Tomas died at the age of 49 in a sporting accident, two years later.

Breeding is not for biginning hobbyists.

This species need relative long incubation period like 27 days or more.

Females mostly grow a bit larger than males and can be agressive to other females or males in small tanks.

More specific info will be placed later.

Remarks :