It is native to southeastern Brazil (north to Bahia), Paraguay, Uruguay and far northeastern Argentina,[1] where it is found in rivers, lakes, and nearby slightly brackish lagoons.

[2][3] It has been introduced to several countries far from its native range, including the United States, Australia, the Philippines, and Taiwan.

Its markings, which cover its body, are bright blue speckles which shine brightly in a healthy fish; they have red fins which may have blueish tones and be tipped in black, but these colours also may change, brighten, or fade depending on the mood.

In a group, they usually pair up once they are around 2–3 in long; at this time they can be quite territorial, and keep other fish away from their breeding space.

In Australia, it has been released into the Tweed River system, New South Wales, and the Swan River system, Western Australia, where it inhabits fresh and brackish water at a wide range of pHs.