Oarfish
A very long, ribbon-shaped ocean fish found around the world outside polar waters.
Fish starting with O
Browse all 45 fish starting with O. Select a name to explore its species profile.
Browse fish A–Z
1,481 speciesChoose a letter to see every fish starting with that letter.
Fish starting with O
45 fish 
Oblique-banded Snapper
An Indo-Pacific snapper ranging from eastern Africa toward Hawaii and the Marquesas, with additional records around the Galapagos.
Ocean Sunfish
A large open-ocean fish found worldwide in tropical and temperate seas, including the Atlantic, Mediterranean and Pacific.
Ocean Triggerfish
Ranges through the western Atlantic and Gulf of Mexico, from Massachusetts toward Brazil.
Oceanic Two-wing Flyingfish
Lives close to the ocean surface in both coastal waters and the open sea.
Ocmulgee Shiner
A Georgia shiner native to the Altamaha and Ogeechee river drainages.
Odontanthias elizabethae
A marine anthias with a natural range restricted to the Hawaiian Islands.
Ohio Lamprey
Found throughout the Ohio River basin across parts of the Midwest and Appalachian states.
Ohrid Trout
Native to Lake Ohrid and its connected waters in Albania and North Macedonia, including the Black Drin River.
Okaloosa Darter
A small freshwater darter with a native range confined to Florida.
Okefenokee Pygmy Sunfish
A tiny southeastern sunfish that favors freshwater habitats with dense plant growth.
Olive Darter
Uses clear, cold water over rock in the Tennessee headwaters and middle Cumberland River system.
Olympic Mudminnow
Favors muddy, heavily vegetated water and can tolerate unusually low oxygen levels.
Onespot Snapper
A snapper ranging from the Red Sea across the Indo-Pacific toward Japan, New Caledonia and Pitcairn.
Ophichthus fowleri
A marine snake eel recorded from Hawaiian waters in the central Pacific.
Opossum Pipefish
Uses quiet stretches of rivers, streams and estuaries where there is little current.
Orange Filefish
An Atlantic filefish found along the Americas from Nova Scotia to Brazil and along western Africa.
Orangebelly Darter
Occupies creek and small-river riffles and runs over gravel and rubble.
Orangefin Darter
Found in the Barren and Green river systems of Kentucky and Tennessee.
Orangefin Madtom
A freshwater catfish native to Virginia and North Carolina.
Orangefin Shiner
Widespread below the fall line in the Mobile basin of Alabama and Mississippi.
Orangemouth Corvina
A croaker native to Mexico’s Pacific coast and Gulf of California, with introduced populations elsewhere.
Orangespotted Filefish
A filefish of shallow tropical and subtropical Atlantic waters, including the Gulf of Mexico and Caribbean.
Orangespotted Sunfish
Favors vegetation in quiet lakes and backwaters, and also tolerates cloudy river water.
Orangetail
Associated with reefs around Hawaii and Johnston Island in the central Pacific.
Orangetail Shiner
A shiner native to southeastern Alabama’s Choctawhatchee River drainage.
Orangethroat Darter
Native to parts of the Mississippi and Lake Erie basins in the central and eastern United States.
Oregon Chub
A small Oregon minnow native to the Willamette River drainage.
Oriental Weatherfish
An introduced loach recorded in several United States states, including Alabama and Georgia.
Ornate Snapper
A colorful snapper recorded from eastern Africa and western Indian Ocean islands toward Japan and the Society Islands.
Oscar
A tropical cichlid with introduced populations in Florida and other warm regions following aquarium releases.
Ostracion whitleyi
A boxfish found around Hawaii, Johnston Atoll, the Marquesas and the Tuamotu Islands.
Ouachita Darter
Uses riffles and fast runs over gravel and pebbles, often in water around three feet deep.
Ouachita Madtom
Known from the upper Saline River forks and an Ouachita tributary in central Arkansas.
Ouachita Shiner
Native only to the upper Little River system in the Ouachita Mountains of Arkansas and Oklahoma.
Owens Pupfish
A desert pupfish whose native range is limited to California’s Owens Valley.
Owens Sucker
Favors finer stream-bottom material rather than coarse gravel and larger rocks.
Oxeye
Uses a broad mix of coastal and inland waters, including mangroves, swamps, rivers, lakes and floodplains.
Ozark Bass
Native to upland portions of the White River system in the Ozarks of Missouri and Arkansas.
Ozark Cavefish
A cave-dwelling freshwater fish with a natural range restricted to the United States.
Ozark Chub
Uses moderate to swift currents over gravel. Activity is greatest during spring and early summer.
Ozark Logperch
A stream fish associated with flowing runs and riffles over gravel.
Ozark Madtom
Favors cool, clear creeks and rivers with relatively steep gradients, using rocky pools and riffles.
Ozark Minnow
A freshwater minnow that spends much of its time close to the bottom.
Ozark Shiner
Lives in the White and Black river systems of southern Missouri and northern Arkansas’s Ozark uplands.