Alternative name Melanorivulus atlanticus. Rivulus atlanticus is described based on specimens collected in the coastal plains of north-eastern Brazil, constituting the first record of the genus for the Atlantic Forest biogeographical province. The new species, together with R. decoratus and R. jalapensis, form a clade of small species, not surpassing 20 mm S.L., mainly diagnosed by the presence of five branchiostegal rays. Rivulus atlanticus differs from those two species by a narrow black border along the entire caudal fin in males and the presence of 2 + 1 neuromasts in the mandibular series.  Rivulus atlanticus also differs from all congeners by having a sexually dimorphic pelvic fin, pointed with seven rays in males, elliptical, and five rays in females. The description of R. atlanticus expands 670 km to the east the known geographic range of the genus.

Keeping and breeding are easy, but a good cover of the aquarium is necessary because their ability to jump, even true the smallest opening, is unbelievable. If there is enough space for the fishes, this species can be housed in a tank with more males than one only combined with several females. If separated before and brought together again, males can become very aggressive and fight to dominate others. An excellent way to get offspring is by bringing a pair or a trio in a small tank from 10 liters with a small filter in it. Some peat moss or dark gravel at the bottom, diffuse light, and a floating "mop" will give space for laying their eggs. If they get a wide variety of life food, the fish will spawn during their whole adult life and produce daily between 5 to 15 eggs. The eggs should be collected by hand and stored for about 14 days in a small container. Eggs are 1.6 mm and amber-colored. It is wise to add Acraflavine to the water you store the eggs to prevent fungi from coming up.

After hatching the young fry can eat fresh artemia nauplii without any problem. It takes 4 to 5 months to raise them to maturity. Often the number of males is far above the number of females. For some species this can become a major problem for the breeder as he has to raise many young fishes and so become able to distribute a few pairs to other hobbyists. Recent personal tests laerned that lower pH levels during the time of hatching gave a higher percentage of females. To achieve this I use some peat moss that I add to the container with the egss just before they are ready to hatch. This peat moss also is a good way to prevent eggs to become attact by fungusses.

There lifespan can be up to 3 years in captivity.

Remarks :