Neofundulus acutirostratus

Neofundulus acutirostratus is a small, sharp-snouted killifish belonging to the family Rivulidae, a group of annual fishes known for their remarkable adaptation to ephemeral wetlands. Like its relatives, this species likely inhabits temporary pools, marshes, and seasonally flooded savanna wetlands within its native range in South America, where its populations are closely tied to the rhythm of wet and dry seasons. Annual killifish such as Neofundulus acutirostratus have evolved a distinctive life-history strategy: adults complete their life cycle within a single rainy season, while drought-resistant eggs remain buried in the substrate to hatch when rains return.

This dependence on intact, undisturbed seasonal wetlands makes the species highly vulnerable to any disruption of its habitat's hydrology. Neofundulus acutirostratus is classified as Critically Endangered (CR) by the IUCN, reflecting a severely restricted range and ongoing pressure from wetland conversion, drainage, and agricultural expansion, which together threaten the temporary pools essential to its survival. Because annual killifish are highly localized, often confined to a handful of pools or a single drainage basin, even modest habitat alteration can eliminate an entire population.

Conservation attention for small-range Neofundulus species has increasingly focused on protecting remaining wetland fragments and encouraging awareness among aquarium hobbyists, who maintain captive lineages of many annual killifish and have, in some cases, helped preserve genetic stock for species facing habitat loss in the wild. This hobbyist-driven ex situ interest offers a genuine, if modest, safety net and represents a hopeful avenue for future collaboration with formal conservation programs. Continued field surveys and habitat protection in its native wetlands remain essential to securing the species' long-term future.

This critically endangered killifish inhabits shallow freshwater pools, temporary wetlands, and slow-moving streams in lowland areas. The species requires clean, well-oxygenated water with abundant aquatic vegetation for breeding and foraging.