The vast majority of beer and wines aren't vegetarian. I believe it is fish bladders that are used to make the drink clearer. What is the vegetarian alternative to this and why isn't it more widely used? Is the veggie option inferior in some way?
From the searchable "is your booze vegan" directory Barnivore website:
It might seem weird at first, but your favourite drink might have more than just alcohol in it.
Brewmasters, winemakers, and distillers may include animal ingredients in their products directly, or they might use them in the processing and filtration.
When making the product, dairy, honey, and other things are ingredients in the final recipe.
When filtering the drinks prior to bottling, companies can use things like isinglass (from fish bladder,) gelatin, egg whites, and sea shells, among other things. These products grab onto the impurities and make it easier to catch them in the filters, though there are many animal-free alternatives in use.