The chub belongs to the Cyprinidae, the largest family of fish in the world. In Switzerland, almost half of the 70 species of fish are Cyprinidae. With its slender body and wide mouth, it is able to adapt easily and find food almost everywhere, the federation said. The chub is also more resistant to disease, parasites and chemical contaminants than other fish. It can also tolerate water temperatures of over 30 degrees Celsius.