The Barcoo River Rainbow is from the Barcoo river in Central Australia. These fish inhabit one of the most unhospitable riverine environments in the world. Water temperatures vary wildly through-out the year.
Overnight low can be about 12 Celsius in summer with a daytime high in the 40s. In winter overnight lows can be below freezing, while the next day can be in the comfortable 20s (Celsius). General water quality is also under pressure as the flow of freshwater is infrequent to say the least.
This means, these rainbows make a very hardy aquarium fish. Able to suffer the consequences of the casual inexperienced fish keeper. A heater is not required under normal conditions for an indoor aquarium.