Two new Rivulus species are described from a single locality in a stream near the village La Guadalupe, Alto Rio Negro, Guainía Dpt., South-eastern Colombia. Rivulus carolinae n. spec. differs from all congeners by combining a relatively small size, unique male color pattern and a characteristic caudal fin shape, and with a unique color pattern in females. Rivulus flammaecauda n. spec., differs by its robust size, by the presence of a unique striped and reticulated pigmentation pattern on the lateral portion of the body and a flame pattern on the caudal fin. The two new species were initially collected from a shallow, slow running, forest creek with black water. The type locality is only 2 km from that of another new species, described in this same volume of Killi Data Series. (Vermeulen & Mejia, 2020)

Keeping and breeding are not easy. A tight-fitting cover on the aquarium is necessary because their ability to jump and escape even by the smallest opening is unbelievable.

If there is enough space for them, this species can be housed in a tank with more than one male and several females. If separated before and brought together again, they can be very aggressive towards each other and fight to become the dominant fish. The best way to produce fry numbers is to put a pair or a trio in a small tank of about 10 liters with a small filter in it or with some aeration. On the bottom of the tank, some peat moss or dark gravel and a floating "mop" give space for laying their eggs. If they are fed a rich variety of live foods, they will spawn during their whole adult life and produce daily between 2 to 3 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 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 outnumber females. For some species, this can become a significant problem for the breeder, as he has to raise many fries to enable distribution of a few pairs to other hobbyists. Recent personal tests found that lower pH levels during hatching gave a higher percentage of females. To achieve this, I used some peat moss to add to the container with the eggs just before they were ready to hatch. This peat moss also is an excellent way to prevent eggs from being attacked by fungus.

Their lifespan can be up to 3 years in captivity.

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