Campellolebias chrysolineatus

Campellolebias chrysolineatus is a small annual killifish belonging to the family Rivulidae, distinguished by the golden-yellow striping along its flanks that gives the species its epithet. Like other annual killifish, it has evolved a remarkable life-history strategy adapted to ephemeral wetland pools: adults complete their entire life cycle within a single wet season, and eggs enter a state of diapause buried in the substrate to survive the dry period before hatching when rains return. This species is restricted to a very small range of temporary freshwater pools and marshy floodplain habitats in South America, where it depends on highly specific hydrological cycles of seasonal flooding and drying.

Its extreme habitat specificity and narrow geographic distribution make it acutely vulnerable to any disruption of its ecosystem. The IUCN Red List classifies Campellolebias chrysolineatus as Critically Endangered, with a population trend that is currently decreasing. Agricultural conversion, drainage of seasonal wetlands, and alteration of natural flooding regimes for farming and water management are the principal drivers of habitat loss across its limited range.

Because the species has such a restricted distribution, even localized disturbances can have outsized effects on its survival prospects. On a more encouraging note, annual killifish species like this one have attracted growing interest from aquarist and ichthyological communities, who maintain captive breeding lines that serve as a genetic safety net and raise awareness of the conservation challenges facing seasonal wetland specialists. Continued field surveys and habitat protection efforts targeting remaining temporary pool ecosystems offer a pathway to stabilizing populations, provided the hydrological integrity of its breeding sites can be preserved.

Protecting the remaining wetland fragments where this species persists remains the most urgent conservation priority.

This critically endangered killifish inhabits shallow freshwater pools, temporary wetlands, and slow-moving streams in coastal lowland areas of southeastern Brazil. The species requires well-vegetated aquatic environments with soft substrates and is adapted to seasonal water level fluctuations in its native wetland systems.