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Fish: different types, definitions, photos, etc.

Fish are the oldest vertebrates, with a wide variety of species. There are about 32,100 named fish species distributed in various waters on the earth, of which there are about 2,500 species in China. Most of them live in seawater, with more than 1,500 marine fish and about 800 freshwater fish. In the past, fish were usually divided into two major categories, cartilaginous fish and bony fish, based on the similarities and differences in the properties of their bones. Characteristics: Aquatic animals (living in water). Skin covered with scales, belonging to cold-blooded animals. Cold-blooded animals with fins (can swim in water) and breathing with gills. Fertilization is external, mainly oviparous, some are viviparous and ovoviviparous.


Fish are a type of aquatic animals under the phylum Vertebrata, which mainly breathe through gills and use fins as the main organ of movement. Fish are the oldest and most diverse group of vertebrates on Earth, widely distributed in environments such as oceans, freshwater lakes and rivers.

  • Scientific name: Pisces (fish is no longer a strict scientific classification, but is used to describe fish in the phylum Vertebrata)

  • Main characteristics:

    1. Aquatic life: Fish live entirely in water.

    2. Gill breathing: Fish absorb oxygen from the water through their gills.

    3. Scale coverage: Most fish are covered with scales for protection.

    4. Function of fins: Use fins for swimming, balance and direction control.

    5. Poikilotherms: Fish body temperature changes with the external environment.

  • Ecological role:

    • Fish are in a key position in the food chain, both as predators and food sources.

    • Help maintain ecological balance, such as controlling algae populations and cleaning waters.

  • Evolutionary history:

    • Fish originated in the Cambrian period about 500 million years ago.

    • It was the first animal to have jaws and vertebrae, laying the foundation for the evolution of other vertebrates.


Fish classification table

Fish can be divided into three major categories based on anatomical and physiological characteristics: cartilaginous fish (such as sharks), bony fish (such as carp) and jawless fish (such as lampreys). The following is a detailed list of fish classification:

Classification levelOrderFamilyGenusExamples
Cartilaginous fishElasmobranchiiCarcharhinidaeCarcharhinusWhite Shark, Blue Shark


PristidaePristisSawfish


RajidaeRajaYellow Spotted Skate
Jawless FishCyclostomataPetromyzontidaePetromyzonLamprey


MyxinidaeMyxineHagfish
Bony fishesCypriniformesCyprinidaeCyprinidae (Cyprinus)Carp, grass carp


SiluridaeSilurusCatfish

PerciformesPercidaePercaPerch, largemouth bass


MoronidaeMoroneSeabass

AnguilliformesAnguillidaeAnguillaEuropean eel, Japanese eel

OsteoglossiformesOsteoglossidaeOsteoglossumDragon fish

ScombriformesScombridaeThunnusTuna, bluefin tuna

ClupeiformesClupeidaeClupeaSardines, herrings

CharaciformesCharacidaeAstyanaxPiranha, Astyanax

Main evolutionary history of fish

1. Origin

Fish are one of the oldest groups of vertebrates on Earth, and the earliest fish fossils can be traced back to the Cambrian period. Jawless fish (such as lampreys and hagfish) are the most primitive fish, followed by cartilaginous fish (such as sharks) and bony fish.

2. Cartilaginous fishes

Cartilaginous fishes (Chondrichthyes) include sharks, rays, etc. Their skeletons are made of cartilage rather than hard bones. These fish play an important role as predators in marine ecosystems.

3. Bony fishes

Bony fishes (Osteichthyes) are the most diverse group of fishes, with a hard bone structure. They have adapted to a variety of water environments, including freshwater and saltwater.

4. Jawless fishes

Jawless fishes are the earliest fishes, and representative species include lampreys and hagfishes. They have no jaws and rely on suction or parasitism for survival.


Ecological role of fish

  1. Important position in the food chain:

    • Predators: such as sharks maintain ecological balance.

    • Food source: such as small fish are food for many aquatic animals.

  2. Environmental health indicators:

    • The number and diversity of fish reflect the ecological health of water bodies.

  3. Resource Utilization:

    • As a source of protein for humans and a target for commercial fishing.


Conservation Status of Fish

  1. Overfishing: Many economic fish are facing the threat of extinction due to overfishing.

  2. Habitat Loss: Pollution and water development have caused serious damage to fish habitats.

  3. Climate Change: Temperature changes and acidified oceans are affecting the distribution and reproduction of fish.

  4. Conservation measures:

    • Establish aquatic conservation areas.

    • Implement sustainable fishing policies.

    • Protect endangered fish populations, such as sturgeons and eels.

Marine fishs Freshwater fish Cypriniformes Siluriformes
Glyptosternum maculatum

Glyptosternum maculatum

Glyptosternum maculatum,Stone flat head

Features:The body surface is smooth and scaleless, the body is elongated, and the ventral surface is flat

It is the species with the highest distribution altitude among the family of fish, and can be found in waters with an altitude of about 4,500 meters.The black-spotted yao mainly lives in rock crevices and feeds on insect eggs or young fish. The number of chromosomes of the black-spotted protist is 2...

Euchiloglanisdavidi(

Euchiloglanisdavidi(

Euchiloglanisdavidi(, Stone Climber

Features:The body is elongated, the head is flat, and the length of the head is about the same as the width of the head

The Latin name of the bluestone catfish is Euchiloglanisdavidi (Sauvage, 1874), which is a fish of the genus Euchiloglanis of the family Euchiloglanidae.The bluestone catfish is a freshwater bottom fish. It is not very active and lives in the caves of rapids, clinging to the stone with its suction c...

Gagata dolichonema

Gagata dolichonema

Gagata dolichonema

Features:The body is long and flat, with narrow dorsal side and wide and flat head and trunk ventrally. The head is flattened laterally and the bone ridges are covered with thin skin.

Latin scientific name of filament black HeiGagata dolichonema,<span style ="background-color: rgb(255, 255, 255); color: rgb(51, 51, 51); font-family: "Helvetica Neue", Helvetica, Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQu...

Liobagrus kingi

Liobagrus kingi

Liobagrus kingi

Features:The adipose fin is connected to the caudal fin with a notch in the middle

King's mullet (Liobagrus kingiTchang,1935) is an animal of the genus Liobagrus in the family Amblycephalus.King's mullet is a small fish that likes flowing water and mainly feeds on aquatic insects and small fish and shrimps.Listed in the second level of the "List of National Key...

Pangasius sanitwongsei

Pangasius sanitwongsei

Giant catfish, Genghis Khan fish

Features:It can grow up to 300 cm long and weigh 300 kg, making it one of the largest catfish in the world.

The Genghis Khan fish is a native fish species of the Mekong and Chao Phraya rivers in Southeast Asia. It is a large carnivorous fish and the most ferocious fish in the entire Mekong and Chao Phraya rivers. It mainly feeds on crustaceans and fish. They are migratory. They usually spawn before the mo...

Silurus mento

Silurus mento

Silurus mento,Kunming-lakecatfish,Dianchi catfish

Features:The body is light yellow, the abdomen is grayish white, and there are irregular spots on the sides of the body.

Kunming catfish (scientific name: Silurus mento), foreign name Kunming-lakecatfish, belongs to the genus Silurus of the family Siluridae of the order Siluriformes, and is endemic to China.Kunming catfish is a carnivorous fish that likes to live in lakeshores with abundant aquatic plants. It hides at...

Mystus guttatus

Mystus guttatus

Mystus guttatus,Sesame, plum blossom, sea bream, sesame sea bream, white-bearded sea bream

Features:Looks like a catfish, once the "king of freshwater"

Mystus guttatus is a species of the genus Mystus in the family Myscidae. It is also called shad, sesame shad, white-bearded shad, and swordfish and pliers in rural Guangdong. It is large in size, with common individuals weighing 1-2 kg, and some large ones weighing 5-10 kg, and the largest can reach...

Yaoshania pachychilus

Yaoshania pachychilus

Yaoshania pachychilus,Panda fish, panda shark, golden band panda climbing rock loach

Features:Its body is distinctly black and white, like a small panda in the water.

The scientific name of the thick-lipped loach is Yaoshania pachychilus (Chen, 1980), a species of fish in the genus Yaoshania of the family Cyprinidae.Thick-lipped Protostomus was discovered by Academician Chen Yiyu in Dayao Mountain, Guangxi, China in 1980. At that time, it was classified under the...

Triphophysa minuta

Triphophysa minuta

Triphophysa minuta

Features:The individual is very small

Triphophysa minuta (Li, 1966) is a small fish of the genus Triphophysa of the family Cobitidae. It lives in a vast area of Xinjiang.Listed in the second level of the "List of National Key Protected Wildlife in China".Protect wild animals and stop eating game.Maintaining ecological balance...

T.xiangxiensis

T.xiangxiensis

T.xiangxiensis, formerly known as Xiangxi blind loach

Features:The pectoral fin grows faster than the body length and can reach the caudal fin

Xiangxi blind loach (T.xiangxiensis) is a fish of the genus T.xiangxiensis of the family Cobitidae. It is a cold-water cave fish that is only distributed in the Yuanjiang River system in Xiangxi, Hunan Province. It is a species endemic to my country.In 1984, the blind fish was discovered in an under...

Triplophysa siluroides

Triplophysa siluroides

Triplophysa siluroides,Catfish, catfish, slab head

Features:The head is large, flat, triangular in dorsal view, with a large, inferior, arc-shaped mouth.

Triplophysa siluroides, scientific name: Triplophysa siluroides (Herzenstein, 1888), is a fish of the genus Triplophysa in the family Cobitidae, and is the largest species in the family Cobitidae.The plateau loach often likes to lurk in the river sections with deep and turbulent gravel bottoms such...

Oreonectes anophthalmusZheng

Oreonectes anophthalmusZheng

Oreonectes anophthalmusZheng

Features:Fish for research purposes, no fishery value

The eyeless loach is named Oreonectes anophthalmusZheng in Latin. The eyeless loach found in Wuming is one of the earliest blind fish species found in my country. It is the second eyeless and pigmentless loach reported in the world. The number is extremely small. The eyeless loach has a very high st...

Leptobotia elongata

Leptobotia elongata

Leptobotia elongata,Flower fish, spotted loach, flower loach, red sand loach, fire army, flower loach

Features:A ferocious bottom-dwelling carnivorous fish, one of the largest loaches in the world

Leptobotia elongata (scientific name: Leptobotia elongata) is a fish of the genus Leptobotia in the family Cobitidae of the order Cypriniformes. It is a giant among loaches and one of the largest loaches in the world.The long thin loach is a warm-water bottom fish that likes to live in the middle an...

Leptobotia  flavolineata

Leptobotia flavolineata

Leptobotia flavolineata,Cow's tail, blind man

Features:There are more than 10 wide yellow-brown horizontal stripes on the sides of the body

The yellow-lined loach (scientific name: Leptobotia flavolineata) is a species of the genus Leptobotia, family Cypriniformes, class Actinopterygii, and is endemic to China.The yellow-lined loach looks very similar to the garfish, but the larger ones are much larger than the garfish. People in...

Leptobotia rubrilabris

Leptobotia rubrilabris

Leptobotia rubrilabris ,Red needle, red lipped loach

Features:Named after the reddish fish mouth

Red-lipped loach, Leptobotia rubrilabris (Dabry de Thiersant, 1872), belongs to the Cypriniformes, Cobitidae, and the genus Leptobotia. It is a fish endemic to the upper reaches of the Yangtze River.The red-lipped loach is larger, second only to the long loach. It has edible value. The population is...

Hypophthalmichthys harmandi

Hypophthalmichthys harmandi

Hypophthalmichthys harmandi,Silver carp, silver carp

Features:It has excellent economic traits such as high fat content, fast growth, large fatness and large trunk.

Hypophthalmichthys harmandi Sauvage, 1884 is a species of the genus Hypophthalmichthys in the family Cyprinidae and is a freshwater economic fish native to Hainan Island, Guangdong.Silver carp is a freshwater economic fish in Hainan Island, Guangdong Province. It mostly lives in open waters with slo...

Procypris mera

Procypris mera

Procypris mera ,Black carp, black carp, black crucian carp, black hook, black carp

Features:The body is laterally flattened and grows in a diamond shape, with a high back bulge, a small head and a long snout.

The Latin name of the black carp is Procypris mera (S. Y. Lin, 1933), and its foreign name is Chinese ink carp. It is a common and high-quality edible fish in Guangxi.Wuyuan carp is a fish in the middle and lower layers of rivers. It mostly lives in water bodies with rocky bottoms deep in the water,...

Procypris rabaudi

Procypris rabaudi

Procypris rabaudi,Rock carp,Water carp, black carp, rock carp, black carp

Features:It has the advantages of small body cavity, tender meat and delicious taste, and is a high-quality economic fish loved by people.

The Latin name of rock carp is Procypris rabaudi, and its foreign name is Rock carp. It is a high-quality economic fish.The rock carp is a wide-temperature fish, and its survival water temperature is 1.5℃-37℃, the living temperature range is 2~ 36℃, and the most suitable feeding temperature is 1...

Mesocyprinus fuxianensis

Mesocyprinus fuxianensis

Mesocyprinus fuxianensis

Features:The body is fusiform, with a groove on the crown of the pharyngeal teeth

Fuxian carp (scientific name: Mesocyprinus fuxianensis), a fish of the class of bony fishes of the phylum Chordata.Fuxian carp is concentrated in the middle and lower layers of the shallow waters along the coast, and a few individuals are also found in the middle and lower layers of the wading area,...

Cyprinus micristius

Cyprinus micristius

Cyprinus micristius,Caihu, Ma fish, Mabian fish, medium carp

Features:The body is similar to that of a carp, with flat sides, a slightly raised back, and a round and straight belly.

Small carp (scientific name: Cyprinus (Mesocyprinus) micristius) is a species endemic to my country, belonging to the subgenus Cyprinus of the genus Cyprinus, subgenus Cyprinus of the genus Cyprinus, subfamily Cyprinidae of the family Cyprinidae.The small carp has a mixed diet, mainly animal bait, m...

Cyprinus pellegrini

Cyprinus pellegrini

Cyprinus pellegrini,Bighead fish, Luyu, Jiangchuan bighead fish, Bell's carp

Features:The body is similar to that of a carp, with a large and wide head that is longer than the body height.

The Latin name of big-headed carp is Cyprinus pellegrini, which belongs to the Cyprinidae family and the Cyprinidae genus.China's rivers and streams have historically been rich in "big-headed carp", but there is no definite research material on when it originated. However, according to...