There are fringe benefits for the chefs, too: When an ingredient is less popular, that usually means that it’s less expensive. And figuring out how to conjure up something irresistible out of, say, a bluefish collar helps break cooks out of culinary ruts. “Yeah, it’s a challenge,” the chef Tom Colicchio said. “What do you do with it? I actually like that: It just forces you to be creative.”

Anyone who has taken a beach vacation knows that clam shacks have been frying up the local catch for ages. At the fancier end of things, elite chefs like Mr. Colicchio, Dan Barber, Eric Ripert, Dave Pasternack, David Chang and Kerry Heffernan have made a point of letting people know that bluefin tuna is not the only fish in the sea.

But lately, the idea of casting a wider net has begun spreading to neighborhood spots, diners and national chains like Slapfish, a growing West Coast enterprise that hopes to open a New York City outpost in 2016.

Louis Rozzo, the president of the F. Rozzo & Sons wholesale distributor in New York and a fourth-generation fishmonger, remembers the sort of comments his family used to hear from chefs: “Who’s going to come to an expensive restaurant and order porgy?” Now, porgy, as well as local tilefile and hake, is in high demand.

“I sell more porgies now by far than I ever have, because people are interested in using something different,” Mr. Rozzo said.

There are many different ways of thinking differently, and locally. At Beachcraft, Mr. Colicchio’s new spot in Miami Beach, the menu makes room for wahoo, cobia, queen snapper, Florida clams and Key West shrimp.

Change is not always easy, especially when customers are in vacation-relaxation mode. “It’s hard because you’re in a hotel and people want the usual things,” said Mr. Colicchio, who has resisted suggestions from the owners of the hotel, 1 Hotel South Beach, that he make room on the menu for a safe bet like salmon.