Campellolebias is a genus of small annual (seasonal) killifish native to southern Brazil, part of the South American annual-killifish lineage of family Rivulidae. The atlas covers 3 species, all in the 1.5–3 in range, all currently assessed as Critically Endangered. Like other annual killifish, they live in temporary pools and roadside ditches on the coastal plains of Rio Grande do Sul that dry out completely for part of the year; the adult fish die with the pool, and the next generation survives as drought-resistant eggs buried in the mud, hatching only once the rains refill the habitat. That makes the whole population at a given site dependent on a single seasonal wetland persisting.
All three Campellolebias species carry a Critically Endangered rating, reflecting how narrow their remaining habitat is: coastal Pampas grassland and wetland in Rio Grande do Sul has been heavily drained and converted to agriculture and development, and a seasonal-pool specialist has nowhere else to go once its pool is filled in. Two of the three species are also flagged in the atlas's CARES conservation-priority list. In the hobby this is a specialist's fish, kept and traded mainly by killifish enthusiasts who raise it from peat-stored eggs; the appeal is closer to ex-situ conservation of an acutely threatened wild population than to display value. The genus has a somewhat tangled taxonomic history, having at times been discussed alongside the closely related, habitat-sharing genus Cynopoecilus.