Ibicuí

The yellow tetra, Hyphessobrycon bifasciatus, is a characid from coastal rivers of southeastern Brazil between Espírito Santo and Rio Grande do Sul. It also occurs in parts of the upper Paraná basin, in floodplain tributaries, lakes and streams, usually under forest cover. Two vertically elongate humeral spots, the front one more prominent, help separate it from similar congeners. Generally peaceful, it is best kept as a group of 8-10 or more.

The dusky millions fish, Phalloceros caudimaculatus, is a small livebearer native to Brazil, Paraguay, Uruguay and Argentina. Feral populations in Australia, New Zealand, Ethiopia and Malawi were purportedly introduced for mosquito control and are now considered invasive. Highly variable in colour pattern, it is known in the hobby in spotted and golden ornamental forms. P. caudimaculatus is the type species of a genus that was monotypic until 21 new species were described in 2008.