The Carp is reputed to be the planets most widespread freshwater fish species. Indeed it is found on every continent except Antarctica. Needless to say it is found throughout the Murray Darling Basin and the Gulf drainages. Originally an ornamental strain was introduced near Sydney about 1850-60. A Singaporean strain was accidentally released in to the Murrumbidgee in 1876. A third introduction occurred in 1961 when a hybrid strain escaped from an aquaculture enterprise into lake Hawthorn near Mildura. These bred and spread up the Murrumbidgee to breed with the Singaporean strain; the result was a strain of carp with a broad genetic make-up, able to cope with a wide range of conditions. The spread of these strong fish was aided by floods, especially those occurring in the mid 1970's.

Carp prefer still or slow moving water and are capable of survival in water of low oxygen levels. Diet is variable and includes molluscs, crustaceans, insect larvae and seeds. Combined with tolerance of adverse water conditions, and a generalist feeding pattern, Carp have high fecundity and potentially rapid growth, making them a highly successful fish. This species is able to feed by sucking in large amounts of sediment, extracting any organic matter and then releasing the sediment via its gills. This activity increases turbidity and the availability of nutrients, thus restricting the growth of aquatic vegetation and increasing the chances of algal blooms.

Carp are a declared noxious pest and must not be translocated or returned to the water alive following capture. Unfortunately, despite this new introductions remain common.