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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
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Rivers and lakes

Fresh water: rivers, streams, lakes and ponds. 423 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 AmazonMekong giant catfishOne of the largest freshwater fishGolden 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

Further reading

GroupSharkRayCarpCatfishSalmonidHerringCodTunaPerch-likeCichlidReef fishEelFlatfishLivebearerAncientOther
UseFood fishFarmedAquarium fishSport fishingCulture and faithVenomous or dangerousInvasiveScience and research
OrderBest knownA to ZOldest firstNewest firstBy size
EuropeCommon rudd A red-finned freshwater fish native to Europe and Asia.Carp · Rivers and lakes 🇲🇾 Malaysia and 1 moreHarlequin rasbora A small, colourful freshwater fish popular in home aquariums for its distinctive black body marking.Carp · Rivers and lakes 🇲🇲 MyanmarOdessa barb Small colourful cyprinid from Myanmar popular in home aquariumsCarp · Rivers and lakes · 2008 🇮🇳 India and 4 moreZebrafish Small striped fish from South Asia kept in aquariums and labsCarp · Rivers and lakes 🇹🇭 Thailand and 2 moreSiamese mud carp Freshwater cyprinid native to Mekong and Chao Phraya riversCarp · Rivers and lakes WorldRasbora A diverse genus of small freshwater fish native to South and Southeast Asia.Carp · Rivers and lakes · 1822 🇨🇳 ChinaTelescope goldfish Fancy goldfish breed with large protruding eyesCarp · Rivers and lakes WorldBarb A common name for various ray-finned cyprinid fish, especially in the genera Barbus and Puntius.Carp · Rivers and lakes Southeast AsiaSiamese algae-eater A bottom-dwelling freshwater fish from Southeast Asia known for eating red algae in aquariums.Carp · Rivers and lakes Southeast AsiaRainbow shark A Southeast Asian freshwater cyprinid kept as a popular but aggressive aquarium fish.Carp · Rivers and lakes 🇹🇭 ThailandRed-tailed black shark A critically endangered Thai carp kept widely in aquariums for its black body and red tail.Carp · Rivers and lakes · 1931 Southeast AsiaClown barb A spotted freshwater fish from Borneo and Sumatra.Carp · Rivers and lakes 🇹🇭 Thailand and 1 moreBala shark A large, silver cyprinid often kept in aquariums despite its size.Carp · Rivers and lakes 🇨🇳 ChinaWhite Cloud Mountain minnow A small, hardy freshwater fish native to China, popular in aquariums for its cold tolerance and peaceful nature.Carp · Rivers and lakes · 1930 🇲🇲 Myanmar and 1 moreCelestial pearl danio A tiny, brightly coloured freshwater fish from Myanmar and Thailand, popular in the aquarium trade.Carp · Rivers and lakes · 2006 🇺🇸 United States and 2 moreFathead minnow Small North American freshwater fish used as bait and in toxicity studies.Carp · Rivers and lakes 🇹🇭 Thailand and 4 moreTinfoil barb A large Southeast Asian freshwater fish known for its red fins and silvery body.Carp · Rivers and lakes · 1853 🇹🇭 Thailand and 4 moreJava barb A silvery freshwater fish farmed across Southeast Asia.Carp · Rivers and lakes 🇮🇩 Indonesia and 1 moreTiger barb Active striped freshwater fish popular in home aquariums.Carp · Rivers and lakes 🇯🇵 JapanKoi Ornamental carp varieties bred in Japan for decorative ponds.Carp · Rivers and lakes 🇨🇳 ChinaGoldfish A domesticated freshwater carp from China, kept worldwide as a pet and aquarium fish.Carp · Rivers and lakes WorldTench Slippery freshwater fish with olive-green skin and red eyes.Carp · Rivers and lakes · 1758

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

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