Lampris guttatus, Lampris spp.




    U.S. wild-caught from Hawaii, California, and surrounding high seas.



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This opah, also known as the moonfish, was caught and released on a longline set off the Channel Islands near California.

This opah, also known as the moonfish, was caught and released on a longline set off the Channel Islands near California.


Opah has been caught incidentally in Hawaii longline fisheries for years. Fishermen once thought that this unusually colorful fish brought good luck, and would give it away as a goodwill gesture rather than sell it. There also wasn’t much of a market for the fish. In the late 1980s, the state of Hawaii started promoting opah to build a market among U.S. consumers for this underutilized species. Today, the demand is rising for opah and its rich, tasty meat.

Opah do not swim in schools, so they’re not caught in great numbers. Individual fish are regularly caught by longliners fishing in the deep ocean for tunas and billfish. While almost all opah sold in the U.S. market are from Hawaii, this species is found worldwide in tropical and temperate waters and is often taken as bycatch by longliners targeting tuna from New Zealand to California. When domestic supplies are low, the United States imports opah, predominantly from Fiji, Tahiti, and New Zealand.

Looking Ahead

In 2004 and 2005, fishermen and fishery biologists reported unusual catches of fish and invertebrates, including opah, in the coastal waters of the eastern and central Gulf of Alaska. These observations coincided with abnormally warm water in the eastern North Pacific Ocean resulting from an overall warming of the whole North Pacific Ocean. The long-term implications of this ocean warming and these changes of distribution and abundance to Alaskan fisheries are not clear. READ MORE



Opah are found in tropical and temperate waters around the world. They live in deep open ocean waters. Opah are capable of traveling long distances, often in response to changing oceanic conditions, such as temperature.



Because opah are not a major commercial seafood species and they live in the deep ocean, scientists know very little about their biology and ecology. They assume opah share general characteristics with other Pacific Ocean pelagic fish (PDF). Scientists estimate that opah grow quickly. Although they’re not sure of opah’s exact life span, scientists age opah by their fin rays, assuming fin ray marks are formed annually. Most opah caught in longline fisheries are estimated to be between 1 and 6 years old. They average about 100 pounds with a diameter of 3 feet.

Opah spawn in warm surface waters throughout the year in the tropics and more seasonally in cooler waters. Opah seem to be very productive, potentially spawning many times throughout the spawning season.



Opah are an unusual looking fish – they have round, flat, body that’s silvery gray in color. Toward the belly, the silver shades to a rose red, dotted with white spots. Its fins and mouth are red, and their large eyes are encircled with gold.



Despite the opah's value to commercial and recreational fishermen, little research on the basic biology and ecology of opah has been conducted. To begin to fill some of the data gaps, NOAA's Southwest Fisheries Science Center began collecting biological samples from opah in 2009 and initiated an electronic tagging program in 2011. Analyses of the biological samples and the data provided by the tagging program have revealed a plethora of information. For example, genetic analysis has determined that there are multiple species of opah—those caught off California are a different species than those caught off Hawaii. Opah also appear to have a unique gill arch structure which has never been seen before.

Scientists plan to continue their study of opah, processing stomachs to identify the species' diet and dissecting gills and whole fish to learn about their anatomy and swimming mechanics. Scientists also hope to continue tagging opah to learn about their movements and range. This research will provide the basic life history information necessary for future population assessments and management. Historical catch data may also show correlations between opah catch and abundance with changes in sea surface conditions such as El Niño and La Niña.



As of 2013, opah populations have never been assessed, but there is no evidence that opah populations are in decline or that fishing rates are too high.



With funding from NOAA's Office of Ocean Exploration, scientists at NOAA's Pacific Islands Fisheries Science Center have conducted tagging studies on opah to learn more about where they live and where they travel. When they catch opah, they tag this fish with a Pop-up Archival Transmitting (PAT) tag then release it back into the ocean. PAT tags stay on the fish for several months then detach, float to the surface, and transmit data on the depth, water temperature, and location occupied by the fish while the tag was attached. From these data, scientists have gained new insights into the depths and water temperatures opah occupy as well as their migration routes. Several opah have showed curious patterns.


Harvesting Opah

There is no directed fishery for opah. In Hawaii, opah is caught on longlines set deep below the surface to target bigeye tuna. Off California, they're taken incidentally in the California drift gillnet fishery targeting swordfish. Since they're highly marketable, fishermen rarely throw opah back.



Who’s in charge? NOAA Fisheries and the Western Pacific Fishery Management Council

Current management: Fishery Ecosystem Plan for Pelagic Fisheries of the Western Pacific Region

No management measures specifically apply to opah. However, general management measures apply to the fisheries that harvest opah.

  • Commercial fishermen must have permits and must maintain logbooks documenting their catch. A limited number of permits are available for the Hawaii and American Samoa longline fisheries to control the number of vessels active in the fishery. 
  • Gear restrictions and operational requirements to minimize bycatch.
  • Longlines are prohibited in certain areas to protect endangered species and reduce the potential for gear conflicts and localized stock depletion (when a large quantity of fish are removed from an area); longline vessels must carry a vessel monitoring system (satellite transponders that provide real-time position updates and track vessel movements) to enforce those area closures.
  • Hawaii- and American Samoa-based longline vessels must carry onboard observers when requested by NOAA Fisheries, in part to record any interactions with sea turtles, seabirds, and marine mammals.
  • Mandatory annual protected species workshops for all longline vessel owners and operators.

Annual Harvest

Compared to targeted tuna, opah are harvested in small but still significant quantities. In 2012, American Samoa fishermen caught 7,507 pounds of opah, and in Hawaii, more than 1.6 million pounds were caught in 2012. 



Opah are particularly valued by the restaurant trade in Hawaii and the continental United States for their high-quality white flesh. The 2012 harvest in Hawaii was valued at more than $3 million.



Although not commonly caught, opah are prized by deepwater recreational anglers for their unique colors and light flavor.



Opah has four types of flesh, each a different color. The tender meat behind their head and along the backbone is orange. Toward the belly, the flesh pales to pink. Opah's cheeks are dark red. All of the meat turns white when cooked, except a small amount of red or liver-colored flesh inside the breastplate, which cooks to a brown color and is somewhat stringy and difficult to fillet.

Opah has a rich, creamy taste and firm, fatty texture. The flavor is distinctive, a cross between tuna and swordfish. The opah’s flesh is rich with healthy oils, and is great grilled, broiled, sautéed, raw, or smoked. (Hawaii Seafood Council, 2011 )



Year-round, but landings seem to peak in April–August



Opah is a rich source of protein, niacin, vitamin B6, vitamin B12, phosphorus, and selenium. It is also low in sodium. Opah provides about 1,800 mg of omega-3s (DHA and EPA) per 4-ounce serving of fresh fish.

Servings 1
Serving Weight 4 oz. (raw)
Calories 170
Protein 24 g
Fat, total 8 g
Saturated fatty acids, total 2.5 g
Carbohydrate 0 g
Sugars, total 0 g
Fiber, total dietary 0 g
Cholesterol 60 mg
Selenium 49 mcg
Sodium 80 mg

Opah Table of Nutrition



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