Austrolebias is a genus of annual killifish in the neotropical annual-killifish lineage (variously placed in family Cynolebiidae or the older, broader Rivulidae), native to seasonal wetlands of the southern Río de la Plata basin - atlas records span Brazil, Uruguay, Argentina, Paraguay, and Bolivia. Atlas species run 1–3.5 in, and like other annual killifish they live in temporary pools that dry out completely each year; adults hatch, grow, and spawn within a single wet season, while drought-resistant eggs survive buried in the mud until the pools refill with the next rains.
Specialist killifish keepers prize Austrolebias for exactly this 'annual' life history - hobbyists commonly trade dormant eggs, shipped dry in peat, rather than live fish, and species such as the Argentine pearlfish (A. bellottii) are among the more established in the hobby for the vivid, often blue-and-orange breeding coloration males develop. Conservation is a genuine concern for the genus: the atlas tally includes 1 Critically Endangered, 2 Endangered, and 5 Vulnerable species among the 15 covered, reflecting how easily seasonal-pool habitat across the Pampas is lost to drainage, agriculture, and altered water flow.