Three-spotted Anostomus

About

Found across a broad sweep of South American river systems, Pseudanos trimaculatus, long known in the hobby under its former name Anostomus trimaculatus, is a mid-sized characin that turns up in the Amazon basin, the Essequibo, the Rupununi, and several other drainages from Guyana down through Peru, Ecuador, and into Argentina. In the wild, adults gather in loose schools of up to fifty individuals in deeper water, grazing on plant material. That social nature is key to understanding how this fish behaves in captivity. Keep too few together and things turn sour fast. Individuals become territorial and persistently aggressive toward tankmates of the same species. Get the numbers up to six or more and the aggression spreads thin enough for a workable group dynamic. Alternatively, a single specimen slots into a community of medium to large fish reasonably well. Good tankmates include larger characins (avoid other anostomids), loricariids, doradids, peaceful cichlids, and knifefish. One caveat worth noting: this species has a habit of nipping fins, so slow-moving or long-finned fish are a poor match. It has not been bred in aquaria, and its care needs put it in intermediate territory. Not brutally demanding, but not a fish to drop into just any community tank without some thought.