Crawfish are freshwater crustaceans that resemble miniature lobsters, ranging in size from 3 1/2 to 7 inches. Over 400 species are found worldwide, 250 of which are in North America, living in rivers, lakes, swamps, canals, wetlands and irrigation ditches. The most important farmed U.S. species is red swamp crawfish (Procambarus clarkii), found in southern Louisiana. Second is the white-river crawfish (P. acutus) from northern Louisiana. Approximately 90 percent of the U.S. farmed and wild crawfish production comes from Louisiana, where crawfish are trapped in the wild and farmed as a rotating crop with rice. Crawfish are also farmed and harvested wild in other southern states and in the Pacific Northwest. In China, crawfish are cultivated in ponds with other fish. In California, fishermen trap coolwater crawfish in rivers that feed the Sacramento Delta. Fishermen in the Midwest trap the species in lakes. Limited amounts are farmed in Europe.