There was a documentary film in 2010 called 'Catfish' about a young man who developed a romance with a woman on Facebook. She turned out to be 40yo married woman when they finally met. There is an explanation about why this film was called Catfish. Copy/paste below link if you're interested in reading it. This film led to a MTV show series called 'Catfish'.

http://www.slate.com/blogs/browbeat/2013/01/18/catfish_meaning_and_definition_term_for_online_hoaxes_has_a_surprisingly.html

btw, 'Catfish' is in the Urban Dictionary online.

Probably not a catfish maybe just a goldfish - when the picture is of the person but not what they look like in this year (or decade) - they have a walking stick and no hair - I usually say I left the iron on and have to dash .................. run like H#ll..

thanks for the info. I never heard of that phrase before today

I thought the reference of 'Catfished' was referring to the whiskers that the fish has making it look like a cat, but is really a fish, and catfish are 'bottom feeders'! The explanation given from the film is a different one though.