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SpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It Again OceanEye to eye with Britain's hidden sharks at SharkAdemy - Oceanographic RiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at all OceanShedd Aquarium Sends Shark Eggs to Bolster Wild Populations SpeciesA 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 Conservation OceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray Area SpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow Reductions FisheriesAdams River Salmon Run in Thompson-Nicola IndiaHilsa production dropped 26% in five years, fisheries minister tells parliament SpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It Again OceanEye to eye with Britain's hidden sharks at SharkAdemy - Oceanographic RiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at all OceanShedd Aquarium Sends Shark Eggs to Bolster Wild Populations SpeciesA 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 Conservation OceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray Area SpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow Reductions FisheriesAdams River Salmon Run in Thompson-Nicola IndiaHilsa production dropped 26% in five years, fisheries minister tells parliament

EveryFish

Deep sea

The dark water below 200 metres, down to the trenches. 44 fish on EveryFish so far.

Below 200 metres sunlight fades, and below about 1,000 metres it is completely dark. The deep sea is cold, under huge pressure and short of food, yet it is the largest living space on Earth and full of fish. In the twilight zone, lanternfish and bristlemouths gather in vast numbers. Deeper down live anglerfish, gulper eels, grenadiers and snailfish, the deepest fish known.

Ways to live in the dark

Many deep-sea fish make their own light, using it as lures, to signal or to hide their outline from below. Big mouths, stretchy stomachs and long teeth help them catch scarce prey. Many have weak muscles and watery bodies to save energy. Some rise towards the surface at night to feed, a daily journey called vertical migration. A snailfish was filmed at 8,336 metres in a trench off Japan in 2022, close to the limit at which fish are thought able to live.

Slow lives and new threats

Deep-sea fish often grow slowly and live long. The orange roughy may live well over a century, and it was heavily fished from the 1980s off New Zealand and Australia before stocks fell. Bottom trawling on seamounts can destroy cold-water corals that took thousands of years to grow. Proposals to mine the deep sea floor for metals are debated: supporters cite the need for battery metals, while scientists warn of damage to little-known habitats.

Famous deep sea fish

Humpback anglerfishHunts with a glowing lure

LanternfishAmong the most numerous fish in the sea

Giant oarfishThe longest bony fish, rarely seen alive

Pelican eelA gulper with a huge mouth Mariana snailfishThe Mariana snailfish of the trenches

Still to be written: Orange roughy, Goblin shark, Frilled shark.

Further reading

Photo credits on this page

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

Ribbonfish: Personnel of NOAA Ship DELAWARE II, Public domain, source
Lanternfish: Emma Kissling, Public domain, source
Oarfish: Sandstein, CC BY 3.0, source
Humpback anglerfish: Emőke Dénes, CC BY-SA 4.0, source
Pelican eel: Unknown author, Public domain, source
Goatfish: Albert Kok at Dutch Wikipedia ( Original text: albert kok ), Public domain, source

The weekly digest

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