Kourou

The false x-ray tetra, Hyphessobrycon simulatus, is a characid endemic to French Guiana, from the Maroni to the Oyapock/Oiapoque river basins. Uncommon in the trade, it was originally described in the genus Pseudopristella. It is told from Pristella maxillaris by a larger humeral spot and black in the anal fin limited to the first ray.

Satanoperca rhynchitis is an eartheater cichlid known only from the Oyapock, Approuague and other river systems of French Guiana. Previously referred to S. jurupari, it was known in the trade as S. sp. 'red lips', and live adults have red lips. Red-lipped fish from Amapá in Brazil appear intermediate between the two, and whether they are hybrids, a distinct species or part of a cline is still unclear.

Hyphessobrycon borealis is a small characid from French Guiana, recorded from the Oyapock/Oiapoque to the Maroni river systems. It inhabits shallow marginal zones with little current, where it forms large schools. The largest recorded specimen measured 27.8 mm, and the species lacks a humeral spot but has an oval spot on the caudal peduncle.