The chefs said they'd avoid tilapia at a restaurant.iStock / Getty Images Plus Business Insider asked chefs to pick the best and worst seafood dishes to order at a restaurant. They said fluke is an underrated fish, and deep-fried calamari may lack flavor. The chefs suggested avoiding seafood specials, as they could be hiding old fish. Grilled mackerel is usually flavorful.Grilled mackerel is best paired with a simple side.unicorn12two/ShutterstockPrivate chef and caterer Priscilla Casey told Business Insider that she'd suggest ordering grilled mackerel."Mackerel is an oily fish, so it binds with seasonings exceptionally well and is usually really flavorful," said Casey.