This fish belongs to the small family of fish referred to as Lampridae or Lamprididae. The genus is known to have only two living fish species.
As a matter of fact, very little is known about the biology or ecology of the moonfish, since it forms only a minor part of the fishery landings and tends to inhabit the deep oceanic waters.
The opah is mostly caught along with other fishes like tuna. Over the years this fish’s demand in the seafood market has rapidly increased owing to its delicious and flavorful meat.
There are four subspecies of the opah fish.
Picture 1 – Opah
Lampris Guttatus: This is the more common and larger subspecies. It inhabits the Western Atlantic, Eastern Atlantic, Gulf of Alaska and Eastern Pacific. They are also found in the temperate waters home to the Indian Ocean.
Lampris immaculatus: This subspecies is also referred to as the Southern Opah. It is mostly found in the Southern Ocean.
Lampris zatima: This is actually an extinct subspecies of the opah fish. From the headless specimens recovered, one can make out that these fishes were very small in size.
Mgalampris keyesi: This is another extinct subspecies of the opah fish. From the fossils recovered, it has been found that this fish was approximately about 4 meters long.
The opah or the moonfish bears a very close resemblance to the large butterfish except for the presence of the ventral fins in the moonfish. This fish has around 14-17 pectoral rays; a major distinguishing feature.
The opah is a round and flat fish with a highly keeled and compressed body. Its body is covered with minute cycloid scales.
This fish has a pointed snout with a small and toothless mouth.
Size: Opah is one such species that is extremely variable in form. Larger species like Lampris guttatus is approximately 6.6 feet (2 meters) long. While the recorded total length of the lesser known Lampris immaculatus is noted to 3.6 feet (1.1 meter).
Weight: These fishes can weigh from 60 to more than 200 pounds.
Color: The opah has a rather conspicuous coloration; its body is attributed with a brilliant deep red- orange color. The color gets somewhat rosy towards the area of the belly. Its flanks are covered with white spots.
Fins: The median as well as the paired fins are bright vermillion. This fish has a long dorsal fin; its pectoral and pelvic fins are long and pointed, while the caudal fin is broadly concave. The anal fin is relatively shorter than the dorsal fin.
Eyes: The eyes of these fishes are large and pronounced, ringed with golden yellow color.
This fish can be found in tropical to temperate waters of majority of the oceans around the world. Typical to a deep water fish, the moonfish dwells in depths of 164 – 1312 feet, with water temperatures ranging from 46 – 72 degrees Fahrenheit.
The geographic range of this fish covers most of tropical and temperate waters of the world’s greatest oceans. Their range extends from the Grand Banks to Argentina in the majestic Western Atlantic; in the Eastern Atlantic the range covers Norway, Greenland, Senegal and further south to Angola. In the Eastern Pacific these fishes inhabit the Gulf of Alaska extending to southern California in the Eastern pacific. The Indian Ocean and Southern Ocean are also home to the opah fish.
Picture 2 – Opah Photo
The moonfish is a strict carnivore. Bulk of the Opah’s diet comprises of squid and krill (euphausiids). At times small fishes are also eaten. Juveniles are known to feed on pelagic invertebrates including crabs, larvae as well as crustaceans like isopods and copepods.
The opah is rich in high quality protein as well as Omega – 3 fatty acids. However it is fatty fish for weight conscious people. This fish is consumed by people in many parts of the world as a common substitute for tuna or salmon. Many salmon and grilled opah fish recipes are available online.
It is important to remember that not much light can be thrown on the biology and reproduction of the opah fish since very little is known about this fish that dwells in deep oceanic waters.
The opah fish reproduce by spawning. These fish are known to spawn over immense areas home to the Pacific, especially in warm surface waters. In the tropics, the spawning season of these fishes lasts throughout the year. However at higher latitudes with sea surface temperatures over 75 degrees Fahrenheit, it tends to get more seasonal.
It has been found that the reproductive rates of these fish are impressively high. In fact the female can spawn several times at intervals of short period, during the season.
The larvae is planktonic and somewhat like those of the ribbonfishes. During the early years of their lives, the slender hatchlings transform and grow at a very fast rate. However, their growth rate gradually lowers after getting transformed into the deep-bodied form.
The opah is seemingly considered to be a solitary fish, though it schools or swims together in groups with other fishes like tuna and scombrids.
Opah fish have a very interesting mode or style of swimming, popularly referred to as the labriform. These fish swim by flapping their pectoral fins. Similarly like tuna, the moonfish swim at high speeds.
The prime predators of the moonfish include huge oceanic sharks like the great white sharks and mako sharks.
These fish migrate over long distances depending on the oceanic environmental conditions.
The moonfish is indeed unique – looking fish backed up by the fact that it is almost entirely flat and round.
Other popular names of this fish include sunfish, redfin ocean pan, kingfish and Jerusalem haddock.
Roughly only 35 percent of this fish’s body is consumable, while the rest comprises of just bones and thick skin.
Not much information is available about the opah fish population; as to whether it is declining or whether they are contributing to overfishing.
Here are some pictures of the gorgeous species known as the opah fish.