A Hawaiian fish traditionally tossed back into the sea by fishermen is appearing as a delicacy on a growing number of city menus.

Local chefs are touting a yellowtail-like Kona Kampachi as a wonder fish — succulent and flavorful, packed with Omega-3 fatty acids, and boasting mercury levels so low, they’re virtually undetectable.

“It is like foie gras without the guilt,” the head chef at Barbounia (250 Park Ave. South at 20th Street, 212-995-0242), Timothy Reardon, said of the Kona Kampachi, which he serves in a Mediterranean-style sashimi dish ($28). “I’m so excited to be a part of bringing it to the New York scene.”

Until recently the Kona Kampachi fed off Hawaiian reefs, a diet that made them inedible due to reef toxins. But two marine biologists, Neil Sims and Dale Sarver, changed all that. In 2001, they began rearing the fish on pellets of fish oil and grain in large cages, submerged in the pristine open waters off of Hawaii’s Kona Coast.

At a fashionable Japanese restaurant in the Chelsea, Morimoto (88 Tenth Ave., between 15th and 16th streets, 212-989-8883), Kona Kampachi is served as sushi and sashimi ($7 a piece). The restaurant’s chef, Masaharu Morimoto, first encountered Kona Kampachi several months ago while on an Iron Chef America program that will air on the Food Network early next year. “It is one of the few fish I like to buy from the U.S. rather than importing from the Tsusjuki fish market in Tokyo,” Mr. Morimoto said. “They do a good job farming it in Hawaii, maintaining excellent quality control.”

The chef de cuisine at Dennis Foy in TriBeCa (313 Church St., between Lispenard and Walker streets, 212-625-1007), Raj Dixit, serves it sliced and dressed with soy sauce, yuzu zest and juice, and olive oil ($14). Meanwhile, it is served as ceviche with mint, yogurt, and fresh lemon ($13.50 a small plate, $16 a large plate) at Crave Ceviche Bar (946 Second Ave. at 50th Street, 212-355-6565) in Midtown. The head chef at Crave Ceviche Bar, Todd Mitgang, said the taste and consistency of the about eight-pound Kona Kampachi is similar to much larger yellowtails that can reach about 100 pounds.

It is the fat content that separates the Kona Kampachi from other white meat fish of the yellowtail family, several chefs said. The fish yields meat made up of about 30% fat, which is double the fat content of sushi-grade yellowtail, Mr. Mitgang said.

Mr. Sims, began his quest to perfect the Kona Kampachi in 2001 after witnessing the marketable success of farmed pearl oysters in the South Pacific, where he worked for the government of the Cook Islands regulating the country’s fisheries. “The financial and economic standards were there,” he said. “The pearl is worth $100 and you still have the oyster.”

With a grant from the federal government, Messrs. Sims and Sarver, spent three years hatching fish, such as snappers and Mahi Mahi, in hopes of discovering a sustainable enterprise. It was the Kona Kampachi, Mr. Sims said, that won the taste test. “He came back hyper-ventilating,” he said, recalling the first time Mr. Sarver tasted the fish.

That tasting led to the founding of Kona Blue Water Farms.

Many chefs and consumers concerned with the environmental and economic impact of fish farming are welcoming the Kona Kampachi to their plates. Unlike farmed salmon, which are generally raised in waters protected by bays where waste and contaminants can bunch up and negatively affect the ecosystem, the Kona Kampachi is reared in open waters that are flushed clean by strong ocean currents, Mr. Sims said. Since the fish is a throwaway among local commercial fisherman, competition with local fisheries is so far insignificant, he said.

With financial backing coming from Kona Blue’s chairman, Thomas McCloskey, who is the former chairman of the highly successful organic food company, Horizon Organic Dairy, Mr. Sims sees a huge market opportunity.

For Mr. Sims, Kona Kampachi is only the beginning. He said he has secured funding from the National Oceanic & Atmospheric Administration to start raising giant grouper, which is widely over-fished in the Gulf of Mexico.

While the Kona Kampachi is hitting plates at high-end restaurants in the city, it has been slow to catch on dramatically in the New York retail market, Mr. Sims said. But with Whole Foods Markets carrying Kona Kampachi on the West Coast and in Florida, Kona Blue’s partners hope the fish will soon be at Whole Foods Markets in the New York area.