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SpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliamentSpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliament
EveryFish

Open ocean

The open sea, far from land, near the surface. 28 fish on EveryFish so far.

The open ocean, far from land, is the largest habitat for fish near the surface. Its sunlit upper layer, down to about 200 metres, is home to fast, wide-ranging fish: tuna, swordfish, marlin, sailfish, mahi-mahi, flying fish and oceanic sharks. Food is patchy, so many of these fish swim great distances, following currents, fronts and schools of smaller prey across whole ocean basins.

Built for distance

Open-ocean fish are streamlined and countershaded, dark above and silver below. Tunas and some sharks keep their muscles warm and never stop swimming. Swordfish and marlin warm their eyes and brain to hunt in cold, deep water. Sailfish are often called the fastest fish, though measured speeds are lower than the popular claims. The ocean sunfish drifts and dives, eating jellyfish. Flying fish glide above the waves to escape predators.

Fishing the high seas

Tuna, swordfish and sharks of the open ocean are caught by longlines and purse seines, often far from any coast, and are managed by regional tuna commissions. Oceanic sharks, such as the oceanic whitetip, have declined steeply. A United Nations treaty on the high seas, adopted in 2023, came into force in January 2026 and allows marine protected areas to be set up in international waters, which cover nearly two thirds of the ocean.

Still to be written: Atlantic bluefin tuna, Skipjack tuna, Swordfish, Indo-Pacific sailfish, Mahi-mahi, Ocean sunfish, Oceanic whitetip shark, Blue shark.

Further reading

GroupSharkRayCarpCatfishSalmonidHerringCodTunaPerch-likeCichlidReef fishEelFlatfishLivebearerAncientOther
UseFood fishFarmedAquarium fishSport fishingCulture and faithVenomous or dangerousInvasiveScience and research
OrderBest knownA to ZOldest firstNewest firstBy size
WorldGreat white shark A large, globally distributed predator known for its size and apex status in marine ecosystems.Shark · Coasts and shelves · 1758 🇺🇸 United States and 3 moreSockeye salmon Anadromous Pacific salmon known for red spawning colour and zooplankton diet.Salmonid · Rivers and lakes · 1792 WorldViperfish Deep-sea fish with fang-like teeth and bioluminescent lures in the genus Chauliodus.Other · Open ocean · 1801 WorldMegalodon Extinct giant mackerel shark from the Miocene to Pliocene epochs.Shark · Coasts and shelves · 1843 🇺🇸 United StatesCladoselache Extinct Late Devonian shark-like fish known for well-preserved fossils and streamlined body.Shark · Coasts and shelves WorldGiant oceanic manta ray The world's largest ray, a massive filter-feeding predator of tropical oceans.Ray · Coasts and shelves · 1827 🇿🇦 South Africa and 4 moreWhale shark The largest living fish species, a gentle giant of tropical oceans.Shark · Open ocean · 1829 WorldMarine hatchetfish Small deep-sea fish with a distinctive compressed body shape and bioluminescent camouflage.Other · Open ocean 🇮🇩 IndonesiaIndonesian coelacanth A rare brown deep-sea fish found in Indonesian waters.Ancient · Open ocean · 1999 WorldAtlantic footballfish Deep-sea anglerfish with a glowing lureOther · Open ocean · 1837 WorldCretoxyrhina Extinct Cretaceous mackerel shark known as the Ginsu sharkShark · Open ocean · 1822 WorldSnailfish A family of marine ray-finned fishes found from shallow coasts to the deepest ocean trenches.Other · Coasts and shelves · 1861 WorldBasking shark The second-largest living fish, a slow-moving filter feeder found in temperate oceans worldwide.Shark · Coasts and shelves · 1765 🇬🇧 United Kingdom and 4 moreLeedsichthys Extinct Jurassic giant filter-feeding fish, the largest known bony fish.Ancient · Open ocean · 1889 🇺🇸 United States and 1 morePacific lamprey An anadromous parasitic jawless fish found along the Pacific Rim.Ancient · Rivers and lakes · 1872 WorldDeepsea lizardfish A deep-ocean predator with a flattened head and large eyes found in tropical seas worldwide.Other · Deep sea · 1878 WorldThaumatichthys A genus of deep-sea anglerfish with a unique internal lure and hinged jaws.Shark · Deep sea · 1908 WorldRibbonfish Deep-sea lampriforms with long, tape-like bodiesOther · Open ocean WorldGlasshead barreleye Deep-sea fish with mirror-based eyesOther · Open ocean WorldChaunax A genus of deep-sea anglerfishes known for their large mouths and luring habits.Shark · Deep sea · 1846 WorldCrestfish Deep-sea ribbon fish with a head crest and ink sacsOther · Open ocean WorldBarreleye Deep-sea fish with tubular eyes and a light-producing anusOther · Open ocean WorldBristlemouths A family of abundant deep-sea fish with bioluminescent organs and bristle-like teeth.Other · Open ocean WorldLanternfish Small bioluminescent mesopelagic fish found in oceans worldwide.Other · Open ocean WorldAnglerfish Ray-finned fish using a modified dorsal fin ray as a lure to catch prey.Other · Coasts and shelves · 1829 WorldOarfish Extremely long pelagic fish known for their ribbon-like bodies and association with sea serpent myths.Other · Open ocean · 1772 WorldHagfish Eel-shaped jawless marine animals known for producing vast amounts of slime.Eel · Open ocean WorldHumpback anglerfish Deep-sea black seadevil with a glowing lureOther · Open ocean · 1863

Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

The weekly digest

Every Monday: the fish of the day, new pages on EveryFish, and the conferences and anniversaries of the week ahead.