Fish That Start With O [Full List]

The world of fish is vast and varied, and there are many species that fall under this category. From the mighty oceanic whitetip shark to the diminutive Owens pupfish, each one has its own distinct characteristics and charm.

So, what makes these fish so special? Some are renowned for their beauty, while others are valued for their commercial importance or the role they play in their ecosystem.

With so much to learn and discover, let’s dive right into this exciting journey of exploration and discovery.

Fish That Start With O

Oarfish

The oarfish, also known as the “king of herrings,” is a large, serpent-like fish that can grow up to 36 feet in length. Its long, ribbon-like body is silver in color, with dark spots along its sides. The oarfish is found in all the world’s oceans, but is rarely seen due to its preference for deep waters. It feeds primarily on plankton and small crustaceans. Despite its intimidating size, the oarfish is not considered a threat to humans.

Ocean Perch

The ocean perch, also known as the rose fish, is a deep-sea fish found in the North Atlantic Ocean. It has a distinctive reddish-pink color and spiky fins. The ocean perch is a popular commercial fish, valued for its firm, white flesh. It feeds on smaller fish and crustaceans, and is often caught using bottom trawls. The fish is also a favorite of recreational anglers, who enjoy its fighting spirit when hooked.

Ocean Sunfish

The ocean sunfish, also known as the mola mola, is one of the largest bony fish in the world, with some individuals weighing over 2,000 pounds. Its body is flattened and circular, with a truncated tail and a distinctive dorsal fin that looks like a giant bump on its back. The ocean sunfish is found in all the world’s oceans and feeds primarily on jellyfish and other soft-bodied creatures. Despite its size, the ocean sunfish is a gentle giant and poses no threat to humans.

Oceanic Whitetip Shark

The oceanic whitetip shark is a large predatory shark found in deep waters around the world. It has a distinctive white-tipped dorsal fin and a sleek, streamlined body. The oceanic whitetip is known for its aggressive behavior and is responsible for numerous shark attacks on humans. It feeds on a variety of prey, including tuna, billfish, and smaller sharks. Unfortunately, the oceanic whitetip shark is also a victim of overfishing and is now considered a threatened species.

Oilfish

The oilfish, also known as the escolar, is a deep-sea fish found in tropical and subtropical waters around the world. It has a long, slender body and is dark in color with a distinctive oily texture. The oilfish is a popular commercial fish, valued for its high oil content and buttery texture. However, the fish is also notorious for causing digestive problems in humans who consume it, due to its high levels of wax esters.

Oldwife

The oldwife, also known as the triple-tail, is a tropical fish found in the Atlantic, Indian, and Pacific Oceans. It has a triangular-shaped body and a distinctive hump on its head. The oldwife is a popular sport fish, known for its acrobatic leaps when hooked. It feeds on small fish and crustaceans and is often caught using live bait or lures.

Old World Knifefish

The old world knifefish, also known as the ghost fish, is a freshwater fish found in rivers and lakes in Africa and Asia. It has a long, slender body and a sharp, pointed head. The old world knifefish is an electric fish, using its electric organ to communicate and navigate in the dark waters where it lives. It feeds primarily on small fish and invertebrates.

Olive Flounder

The olive flounder, also known as the bastard halibut, is a flatfish found in the Pacific and Atlantic Oceans. It has a broad, flattened body and a distinctive diamond-shaped head. The olive flounder is a popular commercial fish, valued for its firm, white flesh.

It is often found buried in sandy or muddy bottoms, where it waits for prey to come within striking distance. The olive flounder feeds on a variety of small fish and crustaceans, and is an important part of many seafood cuisines around the world.

Opah

The opah, also known as the moonfish, is a large, colorful fish found in the open ocean. It has a round, disc-shaped body and is characterized by its bright red coloration and iridescent scales. The opah is an important commercial fish, valued for its firm, flavorful flesh. It feeds on a variety of prey, including squid and other small fish. Despite its popularity, the opah is still relatively unknown to many people due to its deep-water habitat.

Opaleye

The opaleye, also known as the halfmoon, is a small fish found in shallow waters off the coast of California. It has a distinctive crescent-shaped tail and is greenish-brown in color with iridescent scales. The opaleye feeds on algae and small invertebrates and is a popular sport fish among anglers. It is also a popular aquarium fish due to its hardiness and attractive appearance.

Orange Roughy

The orange roughy, also known as the deep-sea perch, is a deep-sea fish found in the Pacific and Atlantic Oceans. It has a distinctive bright orange coloration and can live for up to 150 years, making it one of the longest-lived fish species in the world. The orange roughy is a popular commercial fish, valued for its firm, white flesh. It feeds on small fish and crustaceans and is often caught using bottom trawls. Unfortunately, the fish is also vulnerable to overfishing and is now considered a threatened species.

Orangespine Unicorn Fish

The orangespine unicorn fish, also known as the bluespine unicorn fish, is a tropical fish found in the Pacific Ocean. It has a distinctive horn-like protrusion on its forehead and bright blue and yellow coloration. The orangespine unicorn fish feeds on algae and small invertebrates and is often found in schools. It is also a popular aquarium fish, prized for its unique appearance.

Orangestriped Triggerfish

The orangestriped triggerfish, also known as the clown triggerfish, is a colorful fish found in the Indo-Pacific region. It has a distinctive orange and white striped pattern and a large, powerful jaw that it uses to feed on crustaceans and other small invertebrates. The orangestriped triggerfish is a popular aquarium fish, but can be aggressive towards other fish and should only be kept with compatible tankmates.

Orbicular Batfish

The orbicular batfish, also known as the round batfish, is a tropical fish found in the Indo-Pacific region. It has a round, disc-shaped body and a large, flattened head. The orbicular batfish feeds on small fish and crustaceans and is often found in shallow waters near coral reefs. It is also a popular aquarium fish, prized for its unique appearance.

Orbicular Velvetfish

The orbicular velvetfish, also known as the spongehead, is a small fish found in shallow waters off the coast of Australia. It has a rounded body and a distinctive pattern of blue spots on its velvet-like skin. The orbicular velvetfish feeds on small crustaceans and is often found hiding among rocks and coral. It is not commonly seen by divers or anglers due to its reclusive nature.

Oregon Chub

The Oregon chub is a small freshwater fish found only in Oregon’s Willamette River basin. It has a streamlined body and a distinctive spot on its dorsal fin. The Oregon chub feeds on insects, small fish, and other aquatic invertebrates and is an important food source for larger fish and birds. The Oregon chub was once on the brink of extinction due to habitat loss and overfishing, but thanks to conservation efforts, its population has made a remarkable recovery in recent years.

Orfe

The orfe, also known as the ide or silver orfe, is a freshwater fish found in Europe and Asia. It has a slender, silver body and a small, upturned mouth. The orfe feeds on aquatic insects, crustaceans, and small fish and is often caught by anglers using fly fishing techniques. It is also a popular ornamental fish, prized for its hardiness and attractive appearance.

Oriental Loach

The Oriental loach, also known as the dojo loach, is a small freshwater fish found in East Asia. It has a slender, eel-like body and is characterized by its whisker-like barbels and small, upturned mouth. The Oriental loach feeds on small invertebrates and is often found in slow-moving streams and ponds. It is also a popular aquarium fish, prized for its interesting behavior and ability to clean up algae.

Oscar

The Oscar is a large freshwater fish found in South America. It has a tall, compressed body and is characterized by its bright orange coloration and distinctive black markings. The Oscar feeds on a variety of prey, including small fish, crustaceans, and insects, and is a popular game fish among anglers. It is also a popular aquarium fish, prized for its hardiness and unique appearance.

Owens Pupfish

The Owens pupfish is a small freshwater fish found only in the Owens Valley of California. It has a streamlined body and is characterized by its dark, iridescent coloration and bright blue fins. The Owens pupfish feeds on small invertebrates and is often found in shallow pools and streams. It is also an important indicator species for the health of the Owens River ecosystem and has been the focus of extensive conservation efforts in recent years.

Conclusion:

In conclusion, we have explored some of the most fascinating fish that start with O. From the majestic oarfish to the elusive Oregon chub, each species has its own unique story to tell. Whether you are an angler, a scientist, or simply a lover of nature, there is something here for everyone to appreciate and admire.

So, the next time you find yourself by the water’s edge or staring into an aquarium, take a moment to appreciate the diverse and wondrous world of fish that start with O. Who knows what other treasures await our discovery in this fascinating and endlessly intriguing realm of the natural world?