Newly discovered fish in the Amazon already faces the risk of disappearing, study finds

The specimens analyzed were collected on different expeditions. The holotype — an individual used as a formal reference for the description of the new species — is a 26.8 millimeter male collected in June 2025, in Igarapé Massaranduba, in the Cajari River drainage, in Laranjal do Jari. The study also analyzed specimens collected in 2024 and 2025 in other parts of the region. Among the specimens studied, the largest male had a standard length of 27.8 millimeters, while the largest female reached 20.6 millimeters. Males are also responsible for one of the most striking characteristics of the species: color. They have orange dots arranged longitudinally on the front of the body and oblique bars, also orange, on the back. These characteristics are part of the set used by researchers to position the new fish in the Laimosemion geayi species group. A fish known in only three places So far, science has recorded orange Laimosemion in only three locations in the lower portion of the Cajari River drainage, a tributary of the Amazon Basin, in Laranjal do Jari. The animals were found in puddles close to the main course of streams, in three forested areas. According to the article, these environments had floating aquatic vegetation, clear water with moderate current, sandy or muddy substrate and depths between 0.5 and 1 meter. The known distribution, however, may not represent the entire area occupied by the species. One of the locations is on the edge of the Cajari River Extractive Reserve. The researchers did not find or collect specimens within the conservation unit, but they consider it possible that the fish also occurs within the reserve. “Although we did not collect within the Reserve, our records carried out on the banks suggest that L.ranja may occur within the RESEX”, says Abrantes. Therefore, the team recommends new sampling inside and outside the conservation unit to determine the geographic distribution of the fish with greater precision. Female of the orange Laimosemion species Yuri Abrantes “In our study, we recommend carrying out new field sampling inside and outside the Reserve, aiming to better understand the geographic distribution of the species and support conservation actions, such as, for example, expanding the limits of this conservation unit to protect the new species”, says the researcher. The recommendation also appears in the scientific article. The authors advocate additional surveys in and around the Rio Cajari Extractive Reserve and point to the expansion of the protected area to include an adjacent location as a measure aimed at the long-term conservation of the species. Discovery and threat go hand in hand If on the one hand the species has just gained a scientific name, on the other researchers have already found signs of degradation in the few places where it is known. “Small fish like these, restricted to small streams or habitats subject to seasonal flooding, are often undersampled, despite their fundamental roles in structuring ecological communities,” explains Abrantes. For the researcher, knowing little about these environments and their inhabitants also makes conservation difficult. “As a consequence, the lack of knowledge tends to increase cases of anthropogenic impacts in the environments where these organisms live.” On expeditions, the team verified different pres-