Mavaca

The gold-striped headstander, Anostomus ternetzi, is an anostomid from the Río Orinoco system and coastal Guyana, Suriname and French Guiana. It lives in rocky areas at the edge of fast-flowing rivers and streams, grazing algae and small invertebrates. Like A. anostomus, it is quarrelsome with conspecifics when only a few are kept. Its distribution in Brazil is unclear, with patchy records from the Araguaia and Xingu basins.

Boulengerella maculata is a pelagic ctenoluciid found throughout much of the Amazon, Orinoco and Tocantins river systems. Colour pattern varies considerably, with some specimens much paler than others, and this may be correlated with water type. Random dark spots on the upper body, and a dark stripe only behind the eye when one is present, separate it from the similar B. lateristriga. It reaches 329 mm SL and needs an aquarium with base dimensions of 240 by 90 cm or more.

The blackwing hatchetfish, Carnegiella marthae, is a small freshwater hatchetfish from the upper Orinoco in Venezuela and the rio Negro in Brazil. It appears to be a stenotypic inhabitant of blackwater, found in igapó and igarapé habitats with overhanging vegetation and leaf litter. Very peaceful but small and timid, it is best kept in a group of 10 or more with similarly sized, peaceful fishes.

Geophagus abalios is a cichlid from black and clear water tributaries of the río Orinoco in Venezuela, across the Llanos and south to the Casiquiare. One of the more commonly-traded members of the genus, it is rarely sold under the correct name and usually misidentified as G. altifrons or G. surinamensis. Juveniles are available cheaply because it is one of the few Geophagus bred commercially. Vertically split anterior flank bars separate it from the very similar G. brokopondo.

Geophagus dicrozoster is a cichlid from tributaries of the río Orinoco in Venezuela, extending to the Casiquiare and the headwaters of the Negro. Commonly traded but rarely under the correct name, it is usually sold as G. altifrons or G. surinamensis, and it is one of the few Geophagus bred commercially. Seven flank bars, the fourth and fifth meeting in a 'Y', and a relatively elongate profile identify it. It appears restricted to acidic blackwater.

Tatia galaxias is a wood catfish from the Orinoco river basin in Venezuela and Colombia, dark with small, round white spots like stars. It is sometimes confused with Tatia intermedia, in which the spots are longer and oval.