There are 26 genera of freshwater crayfish, over 540 species. The Chinese favored is red swamp crayfish,which grow in rivulets with exuberant aquatic plants or in ditches of paddy fields.This foreign invasive species appearing in China not even 40 years,once troubled ordinary people. At that time, rice fields held overabundant crayfish ,to the extent of a disaster.The Chinese approach of wiping out invasive species is easy, brutal and straightforward.Just eat it. https://goo.gl/N55qXQ