Austrofundulus is a genus of annual killifish from the Maracaibo basin region straddling Venezuela and Colombia. All three atlas species live in temporary pools that form in the rainy season and dry out completely for months afterward - the fish itself dies when its pool evaporates, but the population survives as drought-resistant eggs buried in the mud, which pause development in a state of diapause and hatch only when the rains return and refill the pool. Adults reach roughly 3–4 in, sizable for an annual killifish.
That diapause biology has made Austrofundulus limnaeus something of a model species in physiology and developmental biology research, valued for studying how embryos tolerate oxygen deprivation and suspended development - interest that runs well beyond the aquarium hobby, though annual-killifish keepers do maintain the genus too, raising it from peat-stored eggs in the classic killifish-hobby style. One species, Austrofundulus myersi, is assessed Endangered, reflecting the vulnerability of seasonal-pool habitat to drainage and land conversion in the region.