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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

Rivers and lakes

Fresh water: rivers, streams, lakes and ponds. 130 fish on EveryFish so far.

Rivers, lakes, streams and ponds hold less than one per cent of the Earth's water, yet about half of all known fish species live in them. Fresh water is broken into separate basins, and fish that cannot cross between them evolve apart, which is why each river system and lake has its own species. The Amazon, Congo, Mekong and Ganges basins and the great lakes of Africa are the richest.

Life in fresh water

A freshwater fish is saltier inside than the water around it, so it must pump salt in through its gills and pass a lot of dilute urine. Freshwater habitats range from torrential Himalayan streams, where loaches cling to rocks, to warm, still swamps where air-breathing snakeheads, catfish and gouramis thrive. Many river fish time their spawning to floods: the Indian major carps spawn in the monsoon floodwaters, and Mekong fish move into flooded forests.

The most threatened fish

Freshwater fish are declining faster than sea fish. A 2021 report by conservation groups found that about a third of freshwater fish species are threatened with extinction and that 80 had already been declared extinct. Dams block migrations, water is drawn off for farms and cities, pollution and sand mining degrade rivers, and introduced species such as tilapia and African catfish compete with native fish. In India, the rivers of the Western Ghats and the North-East hold many endemic fish at risk.

Famous rivers and lakes fish

RohuA river carp of the Indian subcontinentArapaimaAn air-breathing giant of the AmazonGolden mahseerThe golden mahseer of Himalayan riversNile perchA huge predator of African lakesRed-bellied piranhaA schooling fish of South American riversZebrafishA small fish of South Asian streams

Still to be written: Mekong giant catfish.

Further reading

GroupSharkRayCarpCatfishSalmonidHerringCodTunaPerch-likeCichlidReef fishEelFlatfishLivebearerAncientOther
UseFood fishFarmedAquarium fishSport fishingCulture and faithVenomous or dangerousInvasiveScience and research
OrderBest knownA to ZOldest firstNewest firstBy size
🇺🇸 United States and 4 moreSea lamprey A jawless, parasitic fish native to the Northern Hemisphere that attacks other fish.Ancient · Rivers and lakes · 1758 🇦🇺 AustraliaLungfish Ancient freshwater fish that breathe air and have lobed fins.Ancient · Rivers and lakes 🇷🇺 RussiaSterlet A small Eurasian sturgeon found in rivers flowing to the Black, Azov, and Caspian seas.Ancient · Rivers and lakes · 1758 🇺🇸 United States and 1 moreLake sturgeon A large, long-lived freshwater fish native to North America.Ancient · Rivers and lakes 🇺🇸 United States and 1 moreAtlantic sturgeon A large anadromous fish native to the western Atlantic Ocean and its river systems.Ancient · Rivers and lakes 🇺🇸 United States and 1 moreShortnose sturgeon A small, endangered North American sturgeon with a short snout.Ancient · Rivers and lakes · 1818 🇷🇺 Russia and 2 moreKaluga A massive semi-anadromous sturgeon from the Amur River basin hunted for caviar.Ancient · Rivers and lakes · 1872 🇺🇸 United StatesShovelnose sturgeon Smallest North American freshwater sturgeon, known for its shovel-shaped snout and caviar production.Ancient · Rivers and lakes · 1820 🇺🇸 United StatesPallid sturgeon An endangered North American sturgeon species native to the Missouri and Mississippi river basins.Ancient · Rivers and lakes · 1905 🇲🇽 Mexico and 2 moreTropical gar A small freshwater predator from Central America known for its armored scales and air-breathing ability.Ancient · Rivers and lakes 🇺🇸 United States and 2 moreGar Ancient armored fish with lung-like swim bladders found in North American waters.Ancient · Rivers and lakes · 1758 🇧🇯 Benin and 4 moreSaddled bichir A large African freshwater fish with primitive lungs and multiple dorsal finlets.Ancient · Rivers and lakes · 1845 WorldBichir Ancient African ray-finned fish with multiple dorsal finlets and lung-like air breathing organs.Ancient · Rivers and lakes WorldLamprey Jawless fish with a sucking mouth found in temperate waters worldwide.Ancient · Rivers and lakes 🇧🇷 Brazil and 4 moreMawsonia Extinct giant coelacanth from the Jurassic and Cretaceous periods.Ancient · Rivers and lakes · 1907 🇺🇸 United States and 1 moreKnightia Extinct herring-like fish from the Green River Formation, famous for its abundant fossils.Herring · Rivers and lakes · 1856 🇳🇬 NigeriaGymnarchus African electric fish with a long dorsal fin used for swimming and sensing prey.Ancient · Rivers and lakes · 1829 🇸🇳 SenegalNile bichir An ancient African fish with lungs and armour-like scales.Ancient · Rivers and lakes 🇺🇸 United StatesAmerican paddlefish Ancient freshwater fish with a sensory snout and filter-feeding habits.Ancient · Rivers and lakes · 1792 🇧🇷 Brazil and 1 moreArapaima Large freshwater fish from the Amazon basin known for its size and air-breathing ability.Ancient · Rivers and lakes 🇸🇳 Senegal and 3 moreWest African lungfish Air-breathing freshwater fish from AfricaAncient · Rivers and lakes 🇷🇺 Russia and 4 moreSiberian sturgeon Large freshwater sturgeon native to Siberian riversAncient · Rivers and lakes 🇸🇳 Senegal and 3 moreSenegal bichir Ancient African fish that breathes air and walks on landAncient · Rivers and lakes 🇦🇴 Angola and 3 moreMarbled lungfish African lungfish with the largest known animal genome, found in East and Central Africa.Ancient · Rivers and lakes 🇨🇳 ChinaChinese paddlefish A giant freshwater predator from China that is now extinct.Ancient · Rivers and lakes · 1862 🇦🇺 AustraliaAustralian lungfish Ancient air-breathing fish endemic to Queensland rivers, known for its longevity and living fossil status.Ancient · Rivers and lakes · 1871 🇺🇸 United States and 1 moreSpotted gar A small North American freshwater fish with a long snout and spotted scales.Ancient · Rivers and lakes · 1860 🇺🇸 United States and 1 morePacific lamprey An anadromous parasitic jawless fish found along the Pacific Rim.Ancient · Rivers and lakes · 1872 WorldArowana Freshwater bony fish with a toothed bone in the mouth and air-breathing ability.Ancient · Rivers and lakes · 1831 🇮🇩 Indonesia and 4 moreAsian arowana Large freshwater fish from Southeast Asia known for its metallic scales and cultural significance.Ancient · Rivers and lakes · 1840

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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.