If volume drives freshness and freshness drives quality, then Rex's is probably one of the best places in Dallas to pound some seafood. The seafood shop with tables for casual eating is the best place in Dallas to slurp on oysters from the north. Sandwiches combine fish and shellfish with bacon and bright condiments that work well, and on Friday they serve a ridiculously overstuffed lobster-roll.
If you like what you're eating, you can easily take it home. All of their products and fresh fish are available for purchase -- you don't even have to bait a hook.