Cuareim

The green fire tetra, or Rathbun's bloodfin, Aphyocharax rathbuni, is a characid endemic to the Paraguay, Paraná and Uruguay river drainages. It is found in Brazil, Paraguay, Argentina and Uruguay, in streams and rivers shaded by floating or overhanging vegetation. Although suitable for a community aquarium, it has a reputation as a fin-nipper, and long-finned species such as many cichlids and anabantoids should be avoided as tankmates.

The Buenos Aires tetra, Hyphessobrycon anisitsi, is a characid from the Paraná and Uruguay river systems in Brazil, Paraguay, Argentina and Uruguay. A popular and hardy aquarium fish, it is also available as a line-bred albino strain, sometimes traded as 'golden'. It has a reputation for fin-nipping, though mostly when too few are kept or space is limited, and a group of at least 8-10 is the minimum.