Refers to people online who create an elaborate online (but fictional) persona. This is in reference to the 2010 documentary movie “Catfish.”
Taken from one person’s explanation of his wife’s deception of her fictional lives, he tells a story that when live cod were transported from Asia to North America, the fish’s inactivity resulted in mushy flesh in. Fishermen discovered putting catfish in with the cod kept them active. These deceptive people are “catfish,” keeping the rest of people on their toes.