Looking for casual seafood in Dupont Circle on short notice - we headed to Johnny's Half Shell. The starters were terrific. File' gumbo declared delicious and authentic by native bayou boy, and the fried oysters were also a hit - on the small side but plentiful and great deep fried crunch with a just right dipping sauce. (Aside: does anyone make a good hangtown fry anywhere in this region?) For main course the halibut was also wonderful - though the portion could have been "beefed up". The big disappointment was the softshell crabs. For $20 one receives two sauteed small, lightweight crabs, with a couple of tablespoons of corn relish. That's it. They were tasty - not right out of the crabpot by any means, but with enough flavor left to satisfy the immediate craving. Service was very friendly and efficient even with a packed house.