The joke is simple and works on anyone. You ask someone questions do you like fish sticks? They say yes. Then you say, do you like to put fish sticks in your mouth? They say yes. Then you say "What are you, a *** fish!"
Get it? Fish sticks sounds like fish ***...
They're not really saying that Kanye is ***... they're saying that he's overly sensitive and While anyone else in the world would laugh at being the *** of such a silly joke, Kayne would take it to heart and go out of his way trying to prove it's not true. I guess you could relate that to the high visibility of his relationship with Amber as a way of him going above and beyond to stop *** rumors, whether true or not.
The funny part is the *** Fish music video at then end that Kanye makes after he thinks he realizes that he is an actual *** fish. They're poking fun at his constant attempts to understand himself - while missing out on the obvious - and his ultimate failure to see himself for what he really is... They're saying that Kanye is delusional more than anything.
By the way, you can still find the video on Youtube, Fancast and several other blogs.