Well, it doesn't matter, does it? You can't just keep frying something – especially something as delicate as fish – until you're reasonably sure the alcohol is gone. When frying fish, there is a point at which it is done, and seconds after that it is overdone and there's no going back – regardless of how much alcohol is left.

If you've been reading Ochef with any regularity, you know there is essentially no way to get rid of all the alcohol once you've added it to a dish, short of evaporating all the liquid (which we seldom recommend).

In general, beer doesn't have a very high alcohol content – varying from 3% to 8%, and averaging somewhere around 5%. Once you've diluted it with the other ingredients in your batter, it's that much less potent. (Some batters use beer as the only liquid for flavoring and leavening; in others, there is a mixture of water and beer.)

Even though frying is an intense cooking method, it is also a quick method, so you are unlikely to get rid of much of the alcohol. If you are concerned about consuming any alcohol, don't add any. It is all but impossible to get rid of all of it. Fish can be breaded before being fried, you can substitute club soda for beer in your batter, or use any of the many batters that do not include alcohol. Here are two, neither of which includes alcohol: Lemon Batter, and A Tender Batter.