Dwarf Argentine Pearl | Cynolebias nigripinnis

Killifish / Rivulinae / Dwarf Argentine Pearl

Profile: Dwarf Argentine Pearl, Black-finned Pearl
Cynolebias nigripinnis Synonyms: None
Physical description: C. nigripinnis is a smaller species than C. bellotti, although these two species have similar characteristics.  Mature males have a blue-black body color that extends on to the fins.   The body is marked with numerous iridescent, blue-white spots.  Just below the edges of the anal and dorsal fins, these spots run together to form a broken stripe.  The caudal fin has several irregular rows of spots.   Females are dull yellow-gray with irregular dark spots.  The fins are brown-gray.
Size/Length: To 2" (5 cm)
Similar species: Cynolebias bellotti
Habitat: Inhabits rivers and streams with muddy beds that dry up at parts of the year.   South America; Rio Paranà in Argentina
S: bottom
Aquarium: A tank measuring 16" (40 cm) with a capacity of 5 gallons (20 L) is sufficient for a male with one or more females.  If more fish are desired, a larger tank is recommended.   Follow suggestions for C. bellotti .
Water chemistry: pH 5.5-6.7 (6.2), 1-8 dH (4), 60-72°F (16-22°C)
Social behavior: The Dwarf Argentine Pearl is an aggressive species that is best kept in its own tank.   Males may harass unreceptive females excessively.  Do not keep two males in the same tank.
Suggested companions: Possibly small catfish and small schooling fish of the upper swimming levels.
FOOD: Live; insect larvae, insects, worms, crustaceans; flakes.
SEX: Males are increasingly more colorful as the spawning season approaches.   Generally males are darker with iridescent spots.
Breeding techniques: A mature pair can be placed in a spawning tank containing a peat or mud substrate and driftwood hiding places for the female.  The water should have a pH around 6.0, a water hardness from 1-4 dH, and a temperature from 68-72°F (20-22°C).  Follow suggestions for C. bellotti, although the peat containing the eggs should be kept in a dark area.  The most peat can be added to a tank containing soft water after a period of 3 months to two or more years.  In order to obtain a healthy brood, the peat or mud should be submersed in water only 1/ 2" to 1" (1.3-2.5 cm) deep.   Start feeding with Artemia nauplii and powdered foods.
Breeding potential: 8.  Breeding is fairly difficult.
Remarks: Formerly two sub-species were known: C. nigripinnis nigripinnis (profiled above) and C. nigripinnis alexandri ; although the latter sub-species is now recognized as a distinct species.
Difficulty of care: 7.  This sensitive species requires well-maintained water with frequent partial water changes.