Cherax is the most widespread genus of fully aquatic crayfish in the Southern Hemisphere. Together with Euastacus, it is also the largest crayfish genus in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies. The most common and widely distributed species in Australia is the common yabby (Cherax destructor). It is generally found in lowland rivers and streams, lakes, swamps and impoundments at low to medium altitude, largely within the Murray–Darling Basin. Common yabbies are found in many ephemeral waterways, and can survive dry conditions for long periods of time (at least several years) by aestivating (lying dormant) in burrows sunk deep into muddy creek and swamp beds. In New Guinea, Cherax crayfish are found widely in rivers, streams and lakes, with a particularly high diversity in the Paniai Lakes. New Guinea is also home to the only known cave-living crayfish in the Southern Hemisphere, C. acherontis. Some species are very colourful and sometimes seen in the freshwater aquarium trade.