Ophthalmolebias bokermanni

Ophthalmolebias bokermanni is a small annual killifish endemic to Brazil, belonging to the diverse Rivulidae family that has radiated extensively across South America's seasonally flooded landscapes. Like other annual killifish, it displays a compact, torpedo-shaped body with the vivid coloration typical of the genus, males typically more brightly patterned than females as an adaptation for mate attraction during their brief adult lifespan. The species inhabits ephemeral pools and marshy depressions within the cerrado biome, wetlands that fill during the rainy season and dry out completely for months at a time.

To survive this cycle, its eggs enter diapause, a dormant state buried in damp substrate, hatching only when rains return and refill the pools, an extraordinary reproductive strategy that has allowed killifish to colonize habitats unsuitable for most other fish. Ophthalmolebias bokermanni is classified as Critically Endangered (CR) by the IUCN, reflecting its extremely restricted range and the fragility of the seasonal wetland habitats it depends on. Agricultural expansion, drainage of wetlands for pasture and cropland, and urban development within the cerrado have steadily eliminated or degraded the isolated pools this species requires, and because populations are highly localized, a single habitat loss event can eliminate an entire population.

On a more encouraging note, growing recognition of cerrado wetlands as critical, underprotected ecosystems has spurred interest from Brazilian conservation groups and specialist aquarist communities, who maintain captive breeding lines that serve as a genetic safeguard and raise awareness of the plight of annual killifish. Continued survey work to locate and protect remaining pool habitats offers a realistic path toward stabilizing this species' future.

This annual killifish inhabits temporary pools and seasonal wetlands in the Brazilian Cerrado savanna. The species requires shallow, ephemeral water bodies that fill during the rainy season and dry completely during drought periods, allowing their drought-resistant eggs to survive in the substrate.