From Fishing Planet Unofficial Wiki

A panfish, also spelled pan-fish or pan fish, is an edible game fish that usually doesn't outgrow the size of a frying pan. The term is also commonly used by anglers to refer to any small catch that will fit in a pan, but is large enough to be legal. However its definition and usage varies with geographical region. According to the Oxford English Dictionary, the term was first recorded in 1796 in American Cookery, the first known cookbook written by an American.

(Source: Wikipedia)