Brazil’s freshwater systems hold an extraordinary diversity of fish, but many of these species are quietly slipping toward extinction as rivers are dammed, fragmented, and polluted. Among them are four threatened species that were the focus of a recent Ex Situ Conservation Assessment (ECA) workshop: three large migratory catfish of the genus Steindachneridion, and one tiny, fast-living annual killifish, Ophthalmolebias constanciae.
While there are plenty of differences between these species, they share a common predicament. Each is endemic to Brazil, each is in decline, and each raises the same question: can ex situ management play a meaningful role in securing their future in the wild?
About the species
The surubim-do-paraíba (Steindachneridion parahybae, Endangered) is a large, nocturnal catfish endemic to the Paraíba do Sul basin in southeastern Brazil. It depends on deep pools and channels near strong rapids, habitats that have been altered or eliminated by the many dams that now exist along the basin. The surubim-do-iguaçu (Steindachneridion melanodermatum, Endangered) faces a similar story in the lower Iguaçu basin, where damming has changed their ideal flowing habitats into still-water reservoirs. This has left its population severely fragmented. Monitoring efforts in 2006 captured just a single individual. The surubim-letra (Steindachneridion scriptum, Vulnerable) faces a similar story. Besides damming, these three species also face threats of combined domestic and industrial pollution, overfishing, and invasive species.
The killifish, peixe-anual or peixe-das-nuvens (Ophthalmolebias constanciae, Critically Endangered) tells a different kind of story. This annual killifish lives in seasonal pools of reddish, acidic water in the coastal plains of Rio de Janeiro state, reaching maturity in just days and dying when the pools dry out—its eggs survive in diapause until the rains return. Once found in several abundant populations, only three remain, as the wetlands it depends on are filled in for real estate expansion or otherwise polluted. Irregular collection by aquarists adds further pressure.
An Ex Situ Conservation Assessment Workshop
From 25 to 28 November 2025, a workshop was held at the ICMBio/CEPTA facilities in Pirassununga, São Paulo, to assess whether—and how—ex situ management could contribute to the conservation of these four species. The workshop was an initiative of ICMBio/CEPTA and ICMBio/DICON, in collaboration with the IUCN SSC Conservation Planning Specialist Group (CPSG) and the São Paulo Zoo (ZooSP), and it was designed and facilitated by Marina Somenzari (IUCN SSC CPSG and ZooSP). It brought together 17 participants representing more than 12 institutions.
The workshop was carried out within the scope of the actions foreseen in four National Action Plans for the Conservation of Threatened Species (PAN) of ICMBio/CEPTA (PAN Paraíba do Sul, PAN Iguaçu, PAN Alto Paraná, and PAN Rivulids), and of the Pró-Pardo Project, with the aim of assessing the feasibility of establishing Population Management Programs, in accordance with ICMBio Normative Instruction No. 05/2021. This Normative establishes the procedures for the creation and implementation of Population Management Programs for Threatened Species of Brazilian Fauna.
To do this, participants followed the IUCN SSC Guidelines on the Use of Ex Situ Management for Species Conservation (2014). The process weighs the potential conservation benefit of each ex situ role against its costs, risks, and likelihood of success, always in integration with conservation actions in the wild, following the One Plan Approach. Through technical presentations, plenary sessions, and working groups, the team identified, species by species, the potential of different ex situ roles. The assessment recommended a clear set of primary roles for each species, including insurance populations, rescue, population restoration, and reintroductions. The detailed consolidated analyses, next steps and recommendations can now be found in the workshop’s report here.
