Marrying shellfish and fin fish with beer can be confusing to the neophyte and quite often perplexing to seasoned beer devotees. For example, swordfish and turbot are miles apart in character. Consider the taste of raw or marinated seafood, or fin fish that is broiled, poached, sauteed, and roasted when you decide which beer will go the best with the dish. For light tasting seafood dishes consider light lagers and pilsners. More flavorful, bold dishes would welcome stronger tasting versions of these types of beer.
Wheat beers can be a wonderful match for shellfish.
We often add a squeeze of lemon on shellfish. Try a squeeze of lemon also in wheat beer. It's quite commonplace. A golden ale like Duvel will complement classic fish dishes and cut through the cream sauce. Many ales make wonderful marriages with these meats.