Hoplisoma oiapoquense

Listed as Least Concern - but read the range before you relax. This species is known from a single river: the Oyapock, the border between Brazil and French Guiana, and only from the upper reaches above the first set of rapids. It's reportedly common where it occurs and has never been found anywhere else.¹ That's a narrower footprint than the status suggests. A fish abundant in one short stretch of one river, and absent from every other, is holding its entire existence in a single basin above a single barrier. Common today doesn't mean buffered against tomorrow.

The fish you're looking at were bred here in Eugene, Oregon - not collected from the wild. Wild imports still reach the hobby, but captive breeding is increasingly what carries this species. For a single-river endemic, that's the difference between a spread bet and one basket.

1. Froese, R. & Pauly, D. (eds). Hoplisoma oiapoquensis. FishBase (2025), citing Nijssen & Isbrücker.