Fun Opah Facts For Kids

Joan Agie
Nov 17, 2022 By Joan Agie
Originally Published on Aug 06, 2021
Edited by Jacob Fitzbright
Fact-checked by Gowri Rao
Opah facts about the first warm-blooded fish discovered.

Opahs are commonly known as sunfish, moonfish, redfin ocean pans, kingfish, and Jerusalem haddock. They are large, deep-bodied, colorful pelagic lamprey fish.

This species was discovered recently to be warm-blooded. The entire core of the body maintains a temperature of 41 degrees Fahrenheit (5 degrees Celsius), which is higher than the temperature of the water around them.

This is the unique feature of the fish as most fish are completely cold-blooded or can warm only some parts of their body. There are two living species recognized, one being Lampris Guttatus and the other one Lampris immaculatus.

Opahs are compressed, disc-shaped, deeply keeled, and colorful fish. They can be in colors like deep red-orange to rosy on the belly with white spots on their flanks.

The paired and median fins are bright orange. This Hawaiian species has large eyes that are distinctive and have golden rings around them.

Their body is covered in minute cycloid scales and has a silvery iridescent guanine coating on it. Opahs are similar in shape to butterfish.

They have a notched forked caudal fin and a curved pectoral fin. They have a falcated pectoral fin with 14-17 rays, which are inserted vertically and not horizontally like other fish. The opah has a single dorsal fin which is long and falcated too and their anal fin is high and long.

Here are some interesting opah fish facts for you. Afterward, do check our other articles on black cod facts and barramundi facts as well.

Opah Interesting Facts

What type of animal is the opah?

The opah is a kind of fish found in both the northern and southern hemispheres. It is a deep water fish known for its disc-like shape. It is the first warm-blooded fish to be discovered and has a small toothless mouth.

What class of animal does the opah belong to?

The opah belongs to the Fish class of the animals. They release spawn like other fish, and the hatching of the eggs happens in the open waters.

How many opahs are there in the world?

The exact numbers are not known for the opah fish's population. As yet, there are not many concerns with regards to its population or habitat loss.

Where does the opah live?

The opah lives in tropical and temperate water around the world. The Lampris immaculatus, known as southern opah or southern moonfish, is found in the southern oceans.

This Hawaiian species can be found near New Zealand as well. The Lampris guttatus is found the world over, from Greenland and  Norway to Angola and Senegal in the Eastern Atlantic, from Grand Banks to Argentina in the western Atlantic.

They are found in the Mediterranean sea too. In the eastern Pacific from the southern Pacific to the Gulf of Alaska, and even in the temperate waters of the Indian Ocean.

What is the opah's habitat?

The opah's habitat is found in the temperate and tropical waters of the world. It is found in the open oceans at the depth of 160-1650 ft (48-500 m) at a temperature of 46.4-71.6 degrees Fahrenheit (8-22 degrees Celsius).

They are found at a depth of 165-330 ft (48-100 m) during the night and 330-1320 ft (100-400 m) during the day.

Who do opahs live with?

Opahs are solitary creatures, but in certain situations, they may be found with tuna or other scombrids.

How long does the opah live?

The opah's lifespan is on average four years and it may live anywhere between one and six years. These estimates are based on the fish that were caught to help estimate the opah's life cycle.

How do they reproduce?

Not much is known about opah's mating rituals. As the fish stays in the deep ocean and its habitat is worldwide, it would be difficult to study the behavior pattern of the opah. They are known to reproduce by spawning.

They spawn in the Pacific ocean, in the warm water on the surface. In the tropical region, they can reproduce throughout the year. At higher latitude, it may become seasonal breeding. The females can spawn many times at short intervals, and the reproductive rate is high too.

The larvae eat plankton to survive and they look like ribbonfish. The larvae will grow at a fast rate. As they get their deep-bodied form, the growth process will slow down.

What is their conservation status?

Opah's conservation status is of the Least Concern according to the IUCN, as they are not much concerned with regards to the decline in their populations. It seems to be stable and increasing.

Opah Fun Facts

What do opahs look like?


Opahs are compresses, disc-shaped, deeply keeled, and colorful fish. They can be in colors like deep red-orange to rosy on the belly with white spots on the flanks. The paired and median fins are bright orange. They have large eyes that are distinctive and have gold rings around them.

Their body is covered in minute cycloid scales and has a silvery iridescent guanine coating on it. They have a silver-gray upper body and a rose-red belly with white spots. Opahs are similar in shape to butterfish.

How cute are they?

They are certainly different-looking creatures, almost like a moon, silvery and colorful as the name moonfish or sunfish suggests.

How do they communicate?

Not much is known about opah's vocal or non-vocal communication. They are known to be solitary creatures living in the deep ocean, which roam a wide area in temperate or tropical waters.

How big is the opah?

The northern opah moonfish is bigger than the southern opah. The northern opahs grow to a length of around 78.7 in (200 cm).

How fast can the opah swim?

The opah moonfish swims by propelling itself by a lift-based dolabriform mode of swimming, which is done by flapping their pectoral fins. This, paired with their forked caudal fins and median fins, allows them to constantly swim at high speeds, like tuna.

How much does the opah weigh?

The northern opah moonfish weighs almost 280-300 lb (127 - 136 kg), and the southern opah's weight is between 66-80 lb (29 - 36 kg).

What are the male and female names of the species?

The male and female of the opah or moonfish having white spots do not have a specific name. They are known as male opah and female opah respectively.

What would you call a baby opah?

The baby opah or moonfish may be called larvae or ribbonfish, because of their shape.

What do they eat?

The opah's diet consists of eating rich food like fish, squid, and euphausiids (krill). The opah is also eaten as food by some people.

Are they dangerous?

They seem to be harmless to humans. It is a unique fish whose behavior pattern should be studied in detail.

Would they make a good pet?

Opah babies are deep water fish, which makes it difficult for them to survive in an aquarium. However, if a similar habitat can be created, they may be able to survive in it.

Did you know...

Opahs exhibit vertical behavior like big-eye tuna and swordfish, which are large pelagic visual predators.

Do people eat opah?

Yes, people love cooking opah and eat opah's meat in various forms like opah steaks, grilled opah, and various other opah recipes. This fish has a rich, creamy, firm, and fatty texture.

The flavor of the opah species is somewhat like tuna and swordfish. Over-eating the opah fish species is not good and this fish should not be eaten more than once every fortnight. It can be eaten raw, smoked, or barbequed.

What fish is similar to opah?

Opahs are delicious and similar to moonfish, swordfish, and so on. You can eat swordfish, tuna, salmon, or any such deep water fish.

How are opahs warm-blooded?

The opah fish species is the only one to exhibit endothermy throughout its body to become fully warm-blooded. The internal organs of this species are kept at a higher temperature than the surrounding water.

It also has regional endothermy, which means its brains and eyes are warmer than the rest of the body as it is fully warm-blooded. The muscles connected to the pectoral fins generate the most heat along with it, the body generates more heat moving.

The thick layer of fat insulates the internal organs and brain. They have a special structure in their gills called rete mirabile, which prevents heat loss in the gills.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other fish including wolffish facts, or loach facts.

You can even occupy yourself at home by coloring in one of our free printable Opah coloring pages.

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Written by Joan Agie

Bachelor of Science specializing in Human Anatomy

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Joan AgieBachelor of Science specializing in Human Anatomy

With 3+ years of research and content writing experience across several niches, especially on education, technology, and business topics. Joan holds a Bachelor’s degree in Human Anatomy from the Federal University of Technology, Akure, Nigeria, and has worked as a researcher and writer for organizations across Nigeria, the US, the UK, and Germany. Joan enjoys meditation, watching movies, and learning new languages in her free time.

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Fact-checked by Gowri Rao

Bachelor of Arts specializing in Economics

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Gowri RaoBachelor of Arts specializing in Economics

With a bachelor's degree in Economics from Krea University, Gowri is a highly skilled data analyst and an expert in regression and causation modeling. Her interests in economic trends, finance, and investment research complement her professional expertise. In addition to her professional pursuits, Gowri enjoys swimming, running, and playing the drums, and she is also a talented tutor.

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