Psectrogaster is a genus of deep-bodied, silvery characiform fish native to river systems across tropical South America, from the Amazon and Orinoco basins south into the Paraná system. Unlike the toothed predators and omnivores that share this broader family grouping on the atlas, Psectrogaster species are detritivores and algae-grazers, with small, toothless, downturned mouths adapted for sifting organic matter and biofilm from sediment and submerged surfaces, a specialised feeding strategy shared with several related South American genera. At up to 10 in, they form a mid-to-large-sized part of these river communities.
These fish carry more ecological and regional food-fishery significance than aquarium interest; several species are harvested locally, particularly in the Amazon basin, but Psectrogaster is essentially absent from the hobby trade and detailed husbandry information is sparse. Conservation data remain limited across the genus, with most of the atlas's eight species Not Evaluated by the IUCN, consistent with a group that has drawn more attention from fisheries science than from taxonomic risk assessment.