Carp were introduced to Australia over 150 years ago but were not seen as a recognised pest species until the ‘Boolarra’ strain appeared in the 1960s. After spreading massively through the Murray–Darling basin, aided by massive flooding in 1974, they have established themselves in every Australian territory except for the Northern Territory. In Victoria, the common carp has been declared a noxious fish species, and the quantity a fisher can take is unlimited. In South Australia, it is an offence for this species to be released back to the wild. An Australian company produces plant fertilizer from carp.