The Wels Catfish is one of the largest freshwater fish in the world. These huge catfish can grow to 10 feet long and weigh 330 pounds. This large size gives them a reputation for being man-eaters. However, the Wels Catfish usually eats frogs, mice, rats, ducks, worms, snails, insects, crustaceans, and fish. But it is possible for a very, very big catfish to eat humans. Man-eating Wels Catfish reports date back to the 15th century. These attacks could have happened during mating season. The Wels Catfish can get aggresive during that time.