Fish include tench, bream, carp and pike. Other commonly cultured fish species include tilapia, catfish, sea bass, carp and bream. Other fish include bass, trout, carp, and walleye. The main commercial species are sturgeon, roach, bream, perch, carp, asp and Wels catfish. The rivers contain fish such as catfish, bass, carp and tilapia. The main types of fish are Tench, Bream, Crucian Carp, Rudd and Carp. The species feeds on a variety of shrimp and fish, including carp and catfish. The lakes are largely populated with carp and catfish. Boilies are popular baits for carp fishing. They are most common on fish with soft fin rays, such as salmon and carp. Traditional Christmas meal in Central Europe is fried carp or other fish. Communities are attempting to contain the spread of the extremely invasive bighead carp. They are hybrids of koi with Asian carp. Introduced species include carp and tilapia, which were introduced in the 1960s. Chickens run free in orchards and ducks and carp populate rice fields.