Order Cyprinodontiformes
Superfamily Cyprinodontoidae
Family Rivulidae
Genus Cynolebias — Cynolebias. Cyn.
Many Aphyosemion species inhabit partially or completely drying forest and savanna puddles in Africa. Similar habitats in Central and South America were colonized by Cynolebias. They inhabit temporarily drying small water bodies on the eastern coast of South America, from the La Plata River estuary almost to the mouth of the Amazon River. Annual fish, living for about 6 months. They grow rapidly due to their short lifespan and therefore always have a great appetite. The body is elongated, with most species having a high back. The dorsal fin is located on the posterior half of the body. The caudal fin is large and fan-shaped. The male is larger than the female. Females have a more modest coloration compared to males and in a number of species are so similar that they can be easily confused.
All Cynolebias can be conditionally divided into two groups: round-finned and long-finned. Round-finned species poorly tolerate prolonged temperature increases beyond 25°C. Anyone keeping these fish should know that they are excellent jumpers, and a poorly covered aquarium lid seems to attract them, so they can find a way to freedom — and death — through the narrowest gap. Many killifish species have a tendency toward cannibalism, eating fry and small fish. Among annual fishes, Cynolebias is particularly noted for this.
Males are aggressive toward each other, while well-fed females are almost always ready for spawning. They prefer live food. Fish stay in the lower water layer. Most species spawn in the substrate. For maintenance, it is better to use a small (15-30 l) aquarium with a soft substrate (boiled peat). A deep layer of peat (4-5 cm) is required because pairs dive deeply together into the peat to deposit their eggs.
They can be kept in a general aquarium with fish of the same size or in a species aquarium, which is preferable. Keep 1 male with several females or a group of fish with a predominance of females (more than 2 males), but in this case, constant skirmishes occur between males, so a large number of shelters (plant thickets, driftwood) is needed. To increase lifespan (up to 8-12 months), females and males are kept separately, only placing them in the spawning aquarium for a short time. Hardness 5-15°, pH 6.5-7.2, temperature 20-24°C; in nature, it can range from 5 to 29°C and more.
Such previously well-known species as Cynolebias adloffi, Cynolebias alexandri, Cynolebias bellottii, Cynolebias nigripinnis are now assigned to the genus Austrolebias. Among the new genera formed from former Cynolebias, Leptolebias, Nematolebias, Megalebias, and Plesiolebias should be noted. From the latter, in turn, the genera Papiliolebias and Stenolebias, distributed in Brazil and Uruguay, have been separated.
— Cynolebias albipunctatus [Costa, 1991]. Code: ALB. (Whitespotted Pearlfish). Northern Brazil. 15 cm. Some females have lateral spots and spots on the caudal peduncle. It is better to keep fish in species aquariums rather than general ones. These should be shaded water bodies with a soft, dark substrate. Surface-floating plants are very good. If keeping with other fish is intended, bottom-dwelling or midwater species should be selected. Since fish are good jumpers, it is necessary to carefully cover the aquarium with a cover glass.
— Cynolebias gilbertoi [Costa, 1998]. Brazil, South America. 6 cm. The body of males has an olive-brown back and an overall blue-gray coloration. A dark stripe runs from the forehead through the eye. Two uneven transverse stripes are located on the fish’s side. The anal fin in males is blue with red rays. The anal and dorsal fins are elongated in males, and rounded in females. During the spawning period, males become almost black. It is best to keep them in a spacious, planted species aquarium. Floating plants on the water surface will not be out of place. Perform partial water changes of up to 20% of the water volume weekly. Do not forget about good filtration and regular aquarium cleaning. They prefer live foods.
— Cynolebias itapicuruensis [Costa, 2001]. Brazil. Length of males up to 12 cm. Females are significantly smaller. This is a robust fish. Body coloration is light brown with narrow vertical golden stripes. Fins are yellow and brown with golden dots, anal fin is greenish-blue. Small black spots are located on the upper part of the head. Vertical black stripes cross the eyes. Pectoral fins are large.
Females have a pale, milky coloration with a silvery sheen over the entire body. Fins are transparent, and like the males, dark vertical stripes cross the eyes. Predatory fish, aggressive and highly territorial. Place 1 male and 2-3 females in the aquarium. They require frequent and abundant feeding. Quite timid, and instead of hiding in plants, they stand near the bottom. They need highly oxygenated water and about 40 liters per pair for maintenance. Sensitive to Odinnium disease. They bury their eggs deep in peat. At 26°C, activity drops significantly; 22-23°C is most optimal. pH 6.8-7.2.
Austrolebias elongates, nigripinnis, robustus, viarius, wolterstorffi. 
