who ever came up with the word donk

I was wondering what is the difference between donk and a fish or are they the same term for noob poker player?

A fish is a player who never seems to know exactly whats up and has to think forever about simple play ( gasping like fish out of water), A donk shoves his or her chips in on draws and other such hands with less then good chances and win most of the time. They drive most learned players absolutly bonkers. And that end our tutorial for today...LOL