Rivulus flavipinnis is originally described in Melanorivulus. Melanorivulus however is considered to be subgenus of the monophyletic genus Rivulus. See: <Melanorivulus> <introduction>

The region comprising the Cerrado savannas of central Brazil has been considered among the most important biodiversity hotspots in the world (Myers et al. 2000), al- though many organisms endemic to this region were insufficiently sampled and poorly known until recent years (Costa et al. 2016). A typical component of the Cerrado fauna is the killifish genus Rivulus Costa, 2006, with species inhabiting the Veredas, a Cerrado ecosystem consisting of small streams running in shallow valleys, often exhibiting the buriti-palm Mauritia flexuosa along their banks (e.g., Costa 2007a; Oliveira et al. 2012). Probably as a consequence of small size, usually not surpassing 45 mm of total length, species of Rivulus occurring in this ecosystem were not rep- resented in collections until recent years, with the great majority of the approximately 40 species occurring in the central Brazilian Cerrado being described only after 2005 (e.g., Costa 2012; Costa et al. 2016). The greatest diversity among species of Rivulus endemic to the Cerrado is concentrated in the central-western Brazilian plateaus, which range in altitudes from 400 to 1,100 m above sea level (asl), in the Caiapó mountain range (Costa 2012). This area is drained by the upper tributaries of the Rio Araguaia, flowing north and belong- ing to the Amazonas–Tocantins river system, and the upper Paraguai and Paraná river basins, flowing southwest and south, respectively, and belonging to the Paraná–Para- guay–Uruguay river systeR. A total of 12 species have been recorded for this area, of which four are endemic to the Araguaia basin, one to the Paraguai basin, and seven to the Paraná basin (Costa 1989, 2005, 2006a, 2007a–b, 2008, 2012). During a recent expedition to this area, three new species were collected, one from the upper Araguaia basin and two from the Paraguai basin. All the three new species are considered to be closely related to R. dapazi, endemic to the Paraguai basin, by all sharing a rudimen tary interarcual cartilage and a dark reddish brown stripe on the distal margin of the anal fin in males (vs. interarcual cartilage well-developed and never a similar stripe on the anal-fin distal margin). This assemblage is hereafter called the R. dapazi species group and the three new species are herein described.

Diagnosis. Melanorivulus ignescens is distinguished from all other species of the M. dapazi group by having the anal fin, in adult males, bright reddish orange (vs. yellow in M. dapazi, M. flavipinnis, and M. regularis). Also distinguished from all other congeners
of the M. dapazi group by the following combination of character states: 5–6 pelvic-fin rays (vs. 7 in M. dapazi and M. regularis); 29–31 scales in longitudinal series (vs. 35–37 in M. regularis); female caudal spot inconspicuous in live fish (vs. conspicuous in M. dapazi and M. regularis); caudal fin, in males, without red bars and distinctive orange margin (vs. with red bars in M. regularis and M. flavipinnis, with broad bright orange band along the whole margin in M. dapazi); in females, ventral surface of the head with dark grey spots, often forming short stripe on the chin (vs. without dark grey spots in M. dapazi); caudal-fin short, its length 26.8–33.1% SL (vs. long, its length 34.1–38.7% SL in M. flavipinnis). Also distinguished from all other species of the M. dapazi group by having a constriction on the metapterygoid (vs. constriction absent).

Keeping and breeding is easy but a tight fitting cover on the aquarium is necessary because their ability to jump, even through the smallest opening, is unbelievable.

This species can, if there is enough space for them, be housed in a tank with more than one male and several females. If separated before and brought together again however, they can be very aggressive towards each other and fight to become the dominant fish. The best way to produce numbers of fry is to put a pair or a trio in a small tank of about 10 litres with a small filter in it or with some aeration. On the bottom of the tank place some peat moss or dark gravel and a floating "mop" to give space for laying their eggs. The fish will, if they are fed a rich variety of live food, 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 coloured. It is wise to add an anti fungus to the water you store the eggs in, to prevent fungal attacks.

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 males far out number females. For some species this can become a major problem for the breeder, as he has to raise many fry to enable distribution of a few pairs to other hobbyists. Recent personal tests found that lower pH levels during the time of hatching gave a higher percentage of females. To achieve this I used some peat moss that I added to the container with the eggs just before they were ready to hatch. This peat moss also is a good way to prevent eggs from being attacked by fungus.

Their lifespan can be up to 3 years in captivity.

Remarks :

Map of Geographical distribution of killifishes of the Rivulus (Melanorivulus) dapazi species group.

Yellow circle: R. ignescens; black pentagon: R. flavipinnis; blue square: R. regularis; red star: R. dapazi.

Blue river drainage: Paraguai;

white river drainage: Araguaia.

Max. size 0.0 cm.
Dorsal 00.0,
Anal 00.0,
D/A 0.0,
LL scale count (average) 00.0
Pre- dorsal length to % SL – 00.0 %
Depth to % SL – 00.0 %