Bryconops marabaixo is a small freshwater fish from the lower Amazon basin, native to the Rio Jari.

The study that described it had the primary purpose of solidifying a proper description for congener Bryconops cyrtogaster, to which it has some superficial resemblance.

[3] The scales are generally silver, with a blue-green tint, and they are darker on B. marabaixo's back; this color changes to a yellowish or pale-brown upon preservation of a dead specimen in alcohol.

The range of B. marabaixo seems to be limited by the Cachoeira de Santo Antônio, a major waterfall in a downstream portion of the Jari.

[13] This park is one of few left in the region that prioritizes biological diversity and preservation, as opposed to sustainable use of natural resources.

[14] Nonetheless, it is under threat of illegal activities that include an unlawful access road that cuts through various protected areas.

[15] While this is not an immediate threat to the aquatic environment of the region, it sets a precedent of deliberate anthropogenic hazard that may eventually extend into B. marabaixo's habitat.