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Freshwater fish

Freshwater fish refers to fish that can live in waters with a salinity of less than 0.05%, or fish that must spend their entire lives in freshwater. There are nearly 3,000 species of fish in my country, of which more than 1,000 are freshwater fish. The more common freshwater fish species include Cypriniformes, Siluriformes, Characidae, Syngnathidae, Amphioxus, etc. Since freshwater environments are smaller in area than oceans but more diverse (rivers, lakes, wetlands, streams, mountain streams, groundwater systems, etc.), freshwater fish present rich morphological and biological diversity under the influence of geographical isolation, climate and hydrological conditions. The following will help your website users understand the evolutionary context and diverse distribution of freshwater fish, and also show their important position in ecology and human society.

I. Introduction to Freshwater Fishes

1. Definition and Key Characteristics

  • Habitat: Freshwater fishes primarily live in low-salinity waters (usually under 0.5‰), including rivers, lakes, swamps, streams, and other inland waters. Some species may frequent estuaries or slightly brackish water.

  • Osmoregulation: To prevent excessive water intake and electrolyte loss, freshwater fishes excrete large amounts of diluted urine and actively retain salts through their kidneys and gills.

  • Diversity: Despite covering a relatively small portion of Earth’s surface, freshwater ecosystems host a remarkable variety of fish species—often due to geographical barriers (waterfalls, river systems) and past climatic/tectonic events. Large lakes in Africa, the Amazon Basin, and Southeast Asian river networks are famous for their high fish diversity and endemism.

2. Major Groups

  • Cartilaginous Fishes (Class Chondrichthyes): Rare in fresh water; only a few examples (such as certain sawfishes or bull sharks) can enter or remain in freshwater habitats.

  • Bony Fishes (Class Osteichthyes): Specifically, the Actinopterygii (ray-finned fishes) dominate most freshwater environments (e.g., Cypriniformes, Siluriformes, Perciformes, Salmoniformes, Osteoglossiformes, etc.).

3. Ecological Value and Human Use

  • Aquatic Ecosystem Balance: Freshwater fishes occupy vital trophic roles, from benthic scavengers to top predators, contributing to nutrient cycling and ecosystem stability.

  • Fisheries and Aquaculture: Freshwater aquaculture (e.g., carp, tilapia, catfish) provides protein and economic benefits worldwide, while wild-capture fisheries also sustain local communities.

  • Ornamental and Cultural Significance: Ornamental fish trade (e.g., koi, goldfish, tropical aquarium species) and recreational fishing (angling) are culturally and economically important in many regions.


II. History and Evolution of Freshwater Fishes

  1. Origins and Early Evolution

  • The earliest jawed vertebrates date back to the Devonian period (around 400 million years ago). Even in these ancient times, freshwater habitats supported primitive fishes.

  • Over subsequent eras (Carboniferous, Permian, Mesozoic), bony fishes (including lungfish, lobe-finned fishes, and later the widespread ray-finned fishes) underwent significant diversification and adaptation to inland waters.

  1. Repeated Geographic Isolation and Adaptive Radiation

  • Continental drift, glaciations, and river system shifts led to the isolation of fish populations, encouraging independent evolutionary paths and high endemism.

  • Examples include African lungfish, South American electric eels, and Southeast Asian fighting fishes (Betta spp.), each illustrating unique adaptations to freshwater environments.

  1. Modern Freshwater Biodiversity

  • Today, freshwater fishes exceed 10,000 known species (about 40–45% of all fish species), yet inhabit less than 1% of Earth’s surface water.

  • Human activities (e.g., dam building, water diversion, pollution, introduction of alien species) now strongly influence many freshwater fish communities, prompting the need for conservation measures.


III. Major Orders and Families of Freshwater Fishes

Below is a classification focusing on bony fishes (Actinopterygii), which comprise the majority of freshwater species. Also included are rare instances of cartilaginous fishes that enter or live in fresh water.

A. Cartilaginous Fishes in Fresh Water (Rare Cases)

OrderFamilyRepresentative GenusExample SpeciesDistribution & Notes
Pristiformes (Sawfishes)Pristidae (Sawfishes)PristisSmalltooth Sawfish (Pristis pectinata), etc.Mostly coastal or estuarine; some individuals migrate into rivers. Overfished, now rare.
Carcharhiniformes (Ground Sharks)Carcharhinidae (Requiem Sharks)Carcharhinus leucas (Bull Shark)Bull Shark (Carcharhinus leucas)Can travel far upriver (e.g., Zambezi), exhibits high tolerance for low salinity waters.

B. Ray-Finned Fishes (Actinopterygii)

1. Order Cypriniformes (Carps, Minnows, Loaches)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Cyprinidae (Carps & Minnows)Cyprinus (Carp), Carassius (Crucian Carp), Hypophthalmichthys (Silver/Bighead Carp), Ctenopharyngodon (Grass Carp)Common Carp (Cyprinus carpio), Goldfish (Carassius auratus), Silver Carp (Hypophthalmichthys molitrix), Grass Carp (Ctenopharyngodon idella)One of the world’s largest freshwater fish families, with major economic and ornamental importance (e.g., koi, goldfish).
(Loach families such as Nemacheilidae, etc.)Triplophysa (Stone Loach, e.g., high-altitude loaches)Tibetan Stone Loach (Triplophysa gigantea), etc.Often inhabiting upland or plateau streams; many species adapted to cold, fast-flowing waters.

2. Order Siluriformes (Catfishes)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Siluridae (Sheatfishes)Silurus (Sheatfish)Amur Catfish (Silurus asotus), Wels Catfish, etc.Common in Eurasian fresh waters, often large-bodied, demersal predators/scavengers.
Clariidae (Airbreathing Catfishes)Clarias (Walking Catfish)African Sharptooth Catfish (Clarias gariepinus), etc.Native to Africa/Asia; possess accessory breathing organs, surviving in low-oxygen conditions.
Ictaluridae (North American Catfishes)IctalurusChannel Catfish (Ictalurus punctatus), etc.Important for aquaculture and recreational fishing in North America.
Callichthyidae (Armored Catfishes)Corydoras (Cory Catfish)Corydoras species (popular in aquariums)South American ornamental fish, equipped with bony plates; popular in hobby aquariums.

3. Traditional Order Perciformes (now extensively revised)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Percidae (Perches)Perca (Perch), Sander (Pike-perch), etc.European Perch (Perca fluviatilis), Walleye (Sander vitreus), etc.Found in cool/temperate Northern Hemisphere waters; prized food and sport fish.
Cichlidae (Cichlids)Oreochromis (Tilapias), Cichla (Peacock Bass), Hemichromis, etc.Nile Tilapia (Oreochromis niloticus), Peacock Bass (Cichla ocellaris), etc.Highly adaptive in Africa and South/Central America; some species (e.g., tilapia) are significant in aquaculture or invasive.
Anabantidae/Osphronemidae (Labyrinth Fishes)Betta (Fighting Fish), Trichopodus (Gouramis), etc.Siamese Fighting Fish (Betta splendens), Three-spot Gourami (Trichopodus trichopterus)Possess auxiliary breathing organ (labyrinth), can survive in oxygen-poor waters; many are ornamental fish.

4. Order Salmoniformes (Salmon, Trout, etc.)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
SalmonidaeOncorhynchus, Salmo, HuchoChinook Salmon (Oncorhynchus tshawytscha), Atlantic Salmon (Salmo salar), Taimen (Hucho hucho), etc.Many are diadromous (breeding in fresh water but maturing in the sea); some remain fully freshwater. High commercial and recreational value.

5. Order Osteoglossiformes (Bonytongues)

FamilyRepresentative GenusExample SpeciesDistribution & Notes
Osteoglossidae (Bonytongues)Scleropages (Asian Arowana), Osteoglossum (Arowana)Silver Arowana (Osteoglossum bicirrhosum), Asian Arowana (Scleropages formosus)Found in South America and Southeast Asia; large ornamental fish prized for coloration and cultural value.

(Additional examples include characins, loaches, knifefishes, etc., found in global fresh waters.)


IV. Conclusion

  1. Multiple Evolutionary Lineages and Broad Diversity

    • Freshwater fishes do not descend from a single clade; they include a few cartilaginous species that tolerate fresh water and a vast array of bony fish orders. Geographical isolation and varied inland water systems have driven high speciation rates and local endemism.

  2. Ecological Functions and Economic Value

    • Freshwater fishes are key components of inland aquatic ecosystems (e.g., controlling algae, recycling nutrients, preying on insects).

    • They also support major industries: aquaculture, wild-capture fisheries, ornamental fish trade, sport fishing, and cultural traditions (e.g., koi, fighting fish).

  3. Conservation and Future Challenges

    • Habitat degradation, pollution, overfishing, and invasive species threaten many freshwater fish populations.

    • Protected river basins, habitat restoration, and breeding-and-release programs for endangered species are crucial for preserving freshwater biodiversity.


Through the above introduction and classification, you can have a more systematic understanding of the distribution and evolution of freshwater fish in modern animal systems, and appreciate their important significance in ecosystems and human society. If you need to further understand specific families, genera or species (such as morphological characteristics, distribution range, conservation status), it is recommended to refer to professional ichthyology books, regional freshwater fish atlases and the latest academic research literature. I hope this "Freshwater Fish Classification Encyclopedia" can meet your needs.

Marine fishs Freshwater fish Cypriniformes Siluriformes
Schizothorax macropogon

Schizothorax macropogon

Schizothorax macropogon,Giant beard bow fish, beard fish

Features:There are two pairs, long, the front of the front of the gill lid at the end of the forefront, and the back of the main gill cover of the main gill cover at the end of the back

Giant Behavior Fish Latin Name Schizothorax Macropogon is a kind of fish that is a fish -shaped carp -shaped carp -shaped carp belly fish.> Giant bearded belly fish is mainly used in water -free vertebrates and aquatic insects in water. The preferences are inhabited by rivers. The water depth is...

Schizothorax chongi

Schizothorax chongi

Schizothorax chongi,

Features:As one of the famous fish of Jinsha River

Schizothorax Chongi (fang), which is a fine -scale split -abdomen, is a unique species in my country.> Fine -scale cracked belly fish is successfully domesticated, and it is carefully cultivated. After the adrenal development is mature, artificial reproduction tests are conducted. From 2005 to 20...

Platypharodon extremus

Platypharodon extremus

Platypharodon extremus,Wide tooth schizothoracin,Flat -pharyng tooth fish, small mouth fish, catfish, grassfish

Features:The back of the body is yellow -brown or lead brown, with a small number of non -obvious block -shaped dark spots, silver white in the abdomen

Polar flat pharyngeal fish Latin scientific name PlatyPharodon Extiremus, foreign name Wide Tooth Schizothoracin, no subspecies.The polar flat pharyngeal fish is mainly aquatic plant corruption and algae, and occasionally eats floating animals and mosquito larvae.The mature male fish has white granu...

Chuanchia labiosa

Chuanchia labiosa

Chuanchia labiosa,Huanghe naked carp,Big mouth catfish, sperm, flower fish, Yellow River fish

Features:Bone lips Yellow River fish is one of the unique fish in the upper reaches of the Yellow River, one of the small economy.

Bone Lip Yellow River Fish Latin scientific name Chuanchia Labiosa, foreign name Huanghe Naked Carp, no subtype.Bone lips Yellow river fish are mainly eaten with raw diatom and insects.Each egg produces about 2700 capsules with a mature female eggs with a length of about 200 mm in length, which is y...

Epalzeorhynchos bicornis Wu

Epalzeorhynchos bicornis Wu

Epalzeorhynchos bicornis Wu,Red Eye Fish, Kok Fish

Features:Smooth, cylindrical. The head is small, the kiss is round and blunt, and there is a active triangular side leaf on each side

Corporal Latin scientific name EpalzeorHynachos Bicornis & Nbsp; WU is a unique species in China.Corner fish is a small freshwater fish, which mainly inhabits the lower layer of the bottom of the rock. Scrape raw algae. The body is small, and the body length is generally 100-150 mm.In recent yea...

Typhlobarbus nudiventris

Typhlobarbus nudiventris

Typhlobarbus nudiventris

Features:When alive, the body is translucent, with a faint reddish tint, and gray-black intestinal contents can be seen in the abdomen

The Latin name of naked blind barb is Typhlobarbus nudiventris, a fish of the genus Typhlobarbus in the family Cyprinidae.The number of naked blind barb is extremely rare. The two specimens obtained later were kept in a ceramic water tank for several days. When at rest, it supports its body with the...

Percocypris tchangi

Percocypris tchangi

Percocypris tchangi

Features:Gill rakers are short, pointed, and sparsely arranged

The Latin name of Zhang's perch is Percocypris tchangi, and the specific epithet is taken from the surname of Zhang Chunlin, a famous Chinese ichthyologist. There was considerable controversy over the classification of Percocypris species, and this species was once considered a synonym of Percoc...

Percocypris pingi retrodorsalis

Percocypris pingi retrodorsalis

Percocypris pingi retrodorsalis,Flower fish, back perch

Features:The dorsal fin is located posteriorly, the snout and mouth are wide, the tentacles are well-developed, and there is a wide black pigment band along the lateral line on both sides of the body

The Latin name of the retrodorsalis percocet is Percocypris pingi retrodorsalis, which is a fish species endemic to the Lancang River and Nu River in China.The diet of the back perch carp is carnivorous, feeding on small fish and shrimps. The common individuals are 3 to 5 kilograms, and the largest...

Percocypris pingi regani

Percocypris pingi regani

Percocypris pingi regani

Features:It has rich meat and is a large economic fish.

The Latin name of the spotted carp is Percocypris pingi regani, a species of fish belonging to the genus Sinapis of the family Cyprinidae of the order Cypriniformes.The spotted carp lives in the middle and upper layers of open water. It moves quickly and is a ferocious fish that specializes in hunti...

Percocyprispingi

Percocyprispingi

Percocyprispingi,Big flower fish, leopard flower fish

Features:A ferocious carnivorous fish, known as the "tiger" of the Jinsha River

Jinsha perch carp, Latin name Percocyprispingi, is a precious, rare and unique indigenous fish in Yunnan.Jinsha perch carp juveniles mostly live along the coast of tributaries or main streams, while adult fish swim in the middle and upper layers of open water areas. It is a fast-moving, ferocious fi...

Scaphesthes macrolepis

Scaphesthes macrolepis

Scaphesthes macrolepis,Largescale shoveljaw fish,Money fish, white-armored fish, red-scaled fish, multi-scaled shovel-jawed fish, multi-scaled proboscis fish

Features:The body is relatively slender and flat on the sides. The back is slightly raised and the abdomen is round.

The Latin name of the multi-scale white snapper is Scaphesthes macrolepis, and the foreign name is Largescale shoveljaw fish, with no subspecies.The multi-scale white snapper is a warm-temperate freshwater fish. It lives in high mountain streams with clear water and sandy and gravelly bottom at an a...

Onychostoma angustistomata

Onychostoma angustistomata

Onychostoma angustistomata,Small mouth white nail, sharp mouth white nail, wax brown

Features:Likes to live in clear, gravelly water.

The Latin name of Sichuan white snapper is Onychostoma angustistomata. It is a medium-sized edible fish in the upper reaches of the Yangtze River. Although its production is not as high as that of white snapper, its meat quality is better. It is one of the fish that people in the production area lik...

Sinocyclocheilus

Sinocyclocheilus

Sinocyclocheilus,Golden thread fish, small hole fish, pineapple fish

Features:The body is long, the sides are flat, the back of the head is significantly bulged and curved, and some are translucent and pink in color.

The Latin name of Sinocyclocheilus is Sinocyclocheilus, which is a general term for fish of the Cypriniformes, Cyprinidae, and Sinocyclocheilus genus.The young golden line barb mainly feeds on zooplankton and aquatic insects, and also eats a small amount of algae and higher plant fragments; the adul...

Luciocyprinus langsoni Vaillant

Luciocyprinus langsoni Vaillant

Luciocyprinus langsoni Vaillant,Luciocyprinus langsoni

Features:The body is long and stick-shaped, slightly flattened behind the dorsal fin, and the abdomen is round and without edges.

The Latin name of the single-striped Luciocyprinus langsoni Vaillant is Luciocyprinus langsoni Vaillant, which is an animal of the Cyprinidae family.Listed in the second level of the "List of National Key Protected Wildlife in China".Protect wild animals and stop eating game.Maintaining ec...

Gobiobotiahomalopteroidea Rendahl

Gobiobotiahomalopteroidea Rendahl

Gobiobotiahomalopteroidea Rendahl,eight-whiskergudgeon,Eight-bearded fish, pike

Features:The body is long and cylindrical, slightly flattened at the rear, with a slender caudal peduncle and 4 pairs of whiskers.

The Latin scientific name of the flat-finned loach is Gobiobotiahomalopteroidea Rendahl, and its foreign name is eight-whiskergudgeon. It belongs to the genus Gobiobotiahomalopteroidea of the family Cyprinidae and is endemic to my country.The flat-finned loach has high requirements for living condit...

Rhinogobio ventralis

Rhinogobio ventralis

Rhinogobio ventralis,Foreign fish, earthworm, long-fin goby

Features:The dorsal fin is long, the back of the body is dark gray with a slight yellow tint, and the abdomen is grayish white.

The long-finned goby, whose scientific name is Rhinogobio ventralis, is a fish of the Cyprinidae family and the genus Rhinogobio, with no subspecies. The long-finned snout goby has a wide range of activities in spring and summer, often foraging in rapids, deep canyons, and tributary outlets. I...

Rhinogobio nasutus

Rhinogobio nasutus

Rhinogobio nasutus,Big nose goby

Features:Very similar to the pigeon fish

The Latin name is Rhinogobio nasutus, which is an aquatic animal belonging to the class of ray-finned fish and is distributed in Gansu and other regions of my country.The specific information is unknown.Listed in the second level of the "List of National Key Protected Wildlife in China".Pr...

Coreius guichenoti

Coreius guichenoti

Coreius guichenoti,Square head water nose, water nose, golden loach, net mouth, twist, fat Tuo, water dense, round mouth copper fish

Features:The body shape is very similar to that of a black carp, but if you look closely, its mouth looks a bit like a carp, and it has a beard.

Coreius guichenoti, Latin name of round-mouthed copper fish, is a fish of Cyprinidae and genus Coreius.Round-mouthed copper fish is an important economic fish in the upper reaches of the Yangtze River. Common individuals are mostly 0.5 to 1 kg, and the largest can reach 3.5 to 4 kg. The artificial d...

Coreius septentrionalis

Coreius septentrionalis

Coreius septentrionalis (Nichols),Northernbronze-gudgeon,Pigeon fish, sand spit, sharp-mouthed water tuna, yellowhead fish (ancient name), northern copper fish

Features:Looks like a cute pigeon from the side

The Latin name of the Northern Bronze-gudgeon is Coreius septentrionalis (Nichols), and its foreign name is Northern Bronze-gudgeon. It is a freshwater fish of the Cyprinidae family of the Cypriniformes order. It is commonly known as the Pigeon Fish and is a species endemic to China.Northern copper...

Anabarilius transmontana

Anabarilius transmontana

Anabarilius transmontana,Mountain Whitefish

Features:The head is blunt, the body is flat, and the peritoneum is gray-black.

Anabarilius transmontana, a species of fish belonging to the Cyprinidae family, is endemic to China.Anabarilius transmontana is a small fish that likes to live in slow-flowing water environments and can grow and reproduce in lakes or rivers. It was once an important fishery target in Datun Lake in Y...

Anabarilius polylepis

Anabarilius polylepis

Anabarilius polylepis,Large white fish, peach white fish, multi-scale white fish

Features:The body is long and flattened, reproduces quickly, and grows fast.

Anabarilius polylepis, the Latin name of the multi-scale whitefish, is a fish species unique to Yunnan, China.The main food of multi-scale whitefish is aquatic plants, followed by small fish and shrimp. 1 winter age can reach sexual maturity, and in early spring every year, the parent fish swims in...