Asterophysus batrachus.

Asterophysus batrachus, commonly referred to as "big mouth whale" by domestic ornamental fish merchants, is a small black catfish of the family Auchenipteridae originating in South America, which is usually only a dozen centimeters long (the largest record is 25 centimeters), but they are terrible predators and are born with insatiable greed. Good appetite. With a large pelvic mouth and a resilient stomach like a rubber bag, these gourmands can swallow large prey and digest it slowly. Sometimes the swallowed fish weighs as much as the catfish itself. Such exceptional phagocytosis earned them the nickname "ogre catfish". Fortunately, it’s just a small fish. If it grows to the size of a silk catfish, a catfish or a giant catfish, it’s likely that it can really swallow people alive.