n2.[countableC] informal someone who lies about themselves on the Internet in order to impress people, especially so that someone will start a relationship with them
Examples from the Corpus
catfish• You meet a man who has a catfish named after him.• Ideal for cichlids and catfishtanks.• I would like to add another catfish.• I have yet to try the wholecharbroiledcatfish.• Check on salttolerance of your fish especially some of the more delicatecatfish before treating.• I lifted out what appeared to be a very large catfish.• A while back, I wrote about my experience of keeping some of the newer catfish on the market.