Alternative name Melanorivulus giarettai.

Rivulus giarettai, from the Araguari river drainage, upper rio Paraná basin, Brazil. This description was the first record of a rivulid in tributaries of the left bank of the Paranaíba river. Rivulus giarettai differs from all other species of the genus Rivulus by possessing an unique color pattern on flank in males, in which red pigmentation is arranged to form a vermiculate pattern. It is similar to species endemic to the central Brazilian
plateau in having ventral process of angulo-articular vestigial, first epibranchial curved, and flank intense greenish blue or greenish golden, to purplish blue above anal-fin base in males; it differs from central Brazilian plateau species by a combination of reduction of black pigmentation on head and humeral region in males, 34-36 scales
on the longitudinal series, 30-32 caudal-fin rays, 3-4 vomerine teeth, and caudal fin with bars in both sexes.

Introduction:

The subgenus Melanorivulus is a speciose South American clade of small killifishes (maximum recorded size of 37.2 mm SL), with over 30 described endemic to the river basins draining the Brazilian Shield (southern tributaries to the Amazonas, Paraná-Paraguay-Uruguay, São Francisco and Parnaíba river basins) (Costa, 2006a). A great diversity of species is concentrated in the Paranaíba River basin (Costa, 1989, 2005, 2007a-b), which is a part of the upper Paraná River basin and occupies a broad geographic area of central Brazil.

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 :

All above info is like the way other members from the Melanorivulus genus act. The species however is not in the hobby yet and so no specific data are available at the moment.

Max. size 3.7 cm.
Dorsal 00.0,
Anal 00.0,
D/A 0.0,
LL scale count (average) 35.0
Pre- dorsal length to % SL – 00.0 %
Depth to % SL – 00.0 %