Argentine pearl (Austrolebias nigripinnis) care guide

Group
Freshwater fish
Other names
Blackfin pearlfish
Family
Rivulidae (New World rivulines)
Origin
Lower Paraná and Uruguay river basins in South America, in temporary ponds and pools that dry out each year.
Water
freshwater
Maximum size
7 cm
Temperature
18–22°C
pH
6–7
Hardness
Soft to medium, 5–12 dGH
Minimum tank
54 litres
Care level
intermediate
Temperament
semi_aggressive
Lifespan
About 1 year years

Care

Still sold almost everywhere as Austrolebias nigripinnis, this small South American pearlfish has been moved to the genus Argolebias, which FishBase now uses (Wikipedia still lists it under Austrolebias). It is the same fish, so look for either name when buying eggs or adults. This is an annual killifish. In the wild it lives in rain-filled pools that dry up each year: the adults die and the eggs wait in the dried mud until the next rains. Expect a life of about a year (the oldest age FishBase records), so plan to collect eggs while the fish are young and in good condition. FishBase notes that it is easy to keep in the aquarium, but the annual life cycle and egg storage make it better suited to someone with a little killifish experience. Keep one male with two or three females, or a pair, ideally in a species tank. Males are territorial and will drive each other, and sometimes females, hard, so give plenty of cover and do not crowd several males together. A tank of around 60 × 30 cm (about 54 litres) suits a trio. Use gentle, air-driven sponge filtration, some plants or a spawning mop for cover, and a layer of peat or another soft substrate the fish can dive into to spawn. A tight-fitting lid is essential, as killifish jump. Unlike most tropical killies, this is a cool-water fish from the subtropics. FishBase gives 18–22 °C, a pH of about 6–7 and soft to moderately hard water (5–12 dGH). It does not need a heater in most heated rooms and does badly if kept too warm. Change part of the water regularly, as the water in a small, well-fed tank fouls quickly. As in other pearlfish, the males are the colourful sex and the females are much plainer. Many related pearlfish look similar, especially the females, so keep it apart from other Austrolebias and Argolebias species. If your fish came with a locality code or collection details, keep that population separate and pass the details on with any eggs or fish you sell. FishBase lists the species as Near Threatened on the IUCN Red List (assessed 2021). The fish and eggs in the hobby are almost all captive bred, often swapped between killifish keepers as eggs in damp peat. Sources: FishBase (fishbase.se/summary/Austrolebias-nigripinnis.html); Wikipedia (en.wikipedia.org/wiki/Austrolebias). Checked October 2026.

Diet

A small predator that eats worms, crustaceans and insects in the wild. Feed mainly live and frozen foods such as bloodworm, Daphnia, brine shrimp and small worms; dry food is usually taken poorly, if at all. Feed generously, as annual killifish grow fast and need plenty of food to reach breeding condition.

Breeding

An annual killifish and a bottom spawner: the pair dive into a soft substrate such as peat and lay their eggs in it. Provide a deep layer of boiled peat (or a container of peat) and let the fish spawn into it for a week or two, then remove the peat, squeeze out excess water and store it just damp in a closed bag or tub at room temperature. FishBase gives an incubation period of 2–4 months. Check the eggs from time to time; once the eyes of the embryos show clearly, wet the peat with cool, soft water to hatch them. Feed the fry newly hatched brine shrimp straight away; annual killifish grow quickly, so feed them little and often.

Compatibility and tank mates

Best in a species tank. Males are territorial and fight each other, so keep one male with two or three females, or several males only in a large, well-planted tank. Its cool water needs and short life rule out most tropical community set-ups. Do not mix with other pearlfish, whose females are very hard to tell apart.

Last updated 4 October 2026. Community-edited care guide on Aquatic-Auctions.

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