"Nobody really wants to advertise that they filter their beer through dead fish"
Well that would be because they don't. Isinglass has a long history of use in beer and wine, and is a refined collagen. If you don't want animal products in beer, awesome, go for it. The slightly hysterical language is unnecessary though.
-- edit -- Another technique sometimes used is to fine with beef gelatin... Not sure how widespread this is commercially, but it seems relatively popular with homebrewers. Vegetarians do need to be careful with beer.