Argentine Pearl | Cynolebias bellottii
Killifish / Rivulinae / Argentine Pearl
Profile: Argentine Pearl
Cynolebias bellottii  Synonyms: Cynolebias gibberosus, C. maculatus, C. robustus
Physical description: This laterally compressed species has rounded fins. Males have an olive-brown back with blue-gray flanks. The body is covered with whitish-blue spots. At spawning times, the male becomes almost black. A dark stripe runs from the forehead through the eye. The dorsal fin is colored like the back, while the other fins are colored like the flanks. Males are paler in color, and often have irregular dark bands on the body.
Size/Length: Males to 2.8" (7 cm), female to 2.3" (6 cm)
Similar species: Cynolebias nigripinnis
Habitat: South America; Rio de la Plata basin.
S: bottom, middle
Aquarium: A tank measuring 24" (51 cm) with a capacity of 10-15 gallons (38-57 L) is sufficient. Use a soft substrate, preferably peat in a tank that is arranged in dark colors. Provide wood and planted areas to serve as hiding areas. Shallow tanks are preferred.
Water chemistry: pH 6-7 (6.5), 2-12 dH (5), 64-75°F (18-24°C)
Social behavior: Males are territorial, intolerant, and aggressive towards one another. Males may harass females around spawning times, so keep one male with several females.
Suggested companions: This fish is best kept in a species tank, although small catfish and schooling fish of the upper swimming levels may be tolerable.
FOOD: Live; insect larvae, insects, worms, crustaceans; flakes.
SEX: Males are larger and darker in body coloring, especially around spawning times.
Breeding techniques: Place an adult pair in a tank (3 gallons is adequate), containing a substrate of peat moss. The water should be soft (2-5°dH) and have a water temperature from 68-77°F (20-25°C). The female may press the eggs into the peat using her anal fins, or the pair may burrow into the substrate, disappearing entirely for short periods of time. Remove the pair from the tank, and then remove the peat. After drying the peat, store it for three to four months. After the time has passed, place the peat in a shallow tank having soft water. To induce hatching, sprinkle small amounts of fine dry food on the surface of the water (See introduction to Killifish). Start feeding with Artemia nauplii. The young grow quickly.
Breeding potential: 7. Breeding is not especially difficult.
Remarks: The Argentine Pearl is an annual species that rarely lives longer than a year even under the best conditions.
Difficulty of care: 5. This species is short-lived and requires frequent partial water changes, combined with well-maintained water conditions.