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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
Carcharodon carcharias

Carcharodon carcharias

Carcharodon carcharias,Great White Shark,Great white shark, white shark, man-eating shark, white shark, man-eating shark

Features:One of the most vicious sharks

The scientific name of the Great White Shark is Carcharodon carcharias, and its foreign name is Great White Shark. There are no subspecies.The relationship between the Great White Shark and other genera in its family is controversial. Two systematic arrangements have been proposed. One holds that it...

Cetorhinus maximus

Cetorhinus maximus

Cetorhinus maximus,Basking Shark,Elephant shark, basking shark, Gan shark, Meng shark, mouse shark, elephant shark, basking shark

Features:The basking shark is the second largest filter-feeding shark in the world after the whale shark.

The Latin name of the basking shark is Cetorhinus maximus, and its foreign name is Basking Shark. There are no subspecies.The basking shark was first described by Gunnerus in 1765 from a specimen in Norway and was originally named Squalus maximus; in the same year, it was changed to the recognized s...

LampetrareissneriDybowski

LampetrareissneriDybowski

LampetrareissneriDybowski,ReissnerLamprey,River lamprey, river lamprey, seven star lamprey, Ray's lamprey

Features:Landlocked type, pale tail fin

The Latin name of Reissner's lamprey is LampetrareissneriDybowski, and its foreign name is ReissnerLamprey. It is a relatively small freshwater species.The Lamprey's lamprey is a relatively small terrestrial species that is semi-parasitic and prefers to live in freshwater streams with slow c...

Lampetra moriiBerg

Lampetra moriiBerg

Lampetra moriiBerg,Seven-star fish, Northeast lamprey

Features:One of two freshwater lampreys

The Northeastern lamprey's Latin name is Lampetra moriiBerg, and it lives in fresh water all its life.Northeast lampreys live in fresh water all their lives, in mountain rivers with microcurrents and sandy bottoms; they burrow into sand or gravel during the day and come out to forage at night; t...

Lampetra japonicaMartens

Lampetra japonicaMartens

Lampetra japonicaMartens,Lamprey, Japanese lamprey

Features:There is a row of 7 separate gill openings behind the eyes. The gill openings and eyes are arranged in a straight line, with a total of 8 eye-like points, so it is commonly called octagonal gills.

The Latin name of Japanese lamprey is Lampetra japonicaMartens, and the species' type origin is in Japan.Japanese lamprey is a carnivorous fish. It lives both independently and parasitically. It often attaches itself to other fish with a sucker and uses the keratin teeth inside the sucker and on...

Pacific Lancelet

Pacific Lancelet

Pacific Lancelet,Bai's lancelet, lancelet, slug, sea worm, pine worm, headless fish, crocodile worm, Xiamen lancelet, etc.

Features:The brain is underdeveloped and the whole body is translucent

The Pacific Lancelet is a warm-temperate marine fish with no subspecies.The origin of Xiamen Lancelet, Liuwudian, Tong'an County, Xiamen City, is known as the hometown of Lancelet. Xiamen Lancelet is also named after the Wenchang Pavilion on the Liuwudian Island.Xiamen lancelets are warm-tempera...

Oncorhynchus

Oncorhynchus

Oncorhynchus,Big fish, Dafaha fish, Guoduo fish, Oyster fish, Chimon fish, Salmon, King salmon

Features:It looks like a bird, with small eyes and a big mouth, and has high nutritional value.

Salmon are distributed on both the east and west sides of the Pacific Ocean. In my country, the largest number of salmon are found in the Heilongjiang River, the Wusuli River, and the Songhua River. They are also found in the Tumen River, the Hunchun River, the Mi River, the Suifen River, the Nen Ri...

Xiphias gladius

Xiphias gladius

Xiphias gladius,swordfish,Swordfish, marlin, blue swordfish, tench

Features:The body is smooth, the back and body are brownish black, the upper jaw is long and pointed, the dorsal fin is small, the mouth is flat, and there are no gills or pelvic fins.

Swordfish (scientific name: Xiphias gladius), also known as "arrowfish". It is a common fish in tropical and subtropical oceans in the world. It is named because its upper jaw extends forward in a sword shape. A "speed comparison table of marine animals" published in the Soviet m...

Xiphias gladius

Xiphias gladius

Xiphias gladius,swordfish,Sailfish, swordfish, marlin, plantain fish, umbrella sailfish, flatfin sailfish

Features:The upper jaw of its mouth is like a sharp sword, and the first dorsal fin is long and tall, like a raised sail or a flag, so people call it sailfish.

There are two common types of sailfish: the oriental sailfish and the gray sailfish. Also known as flat sail, swordfish, and swordfish. Sailfish are river fish, and are pelagic fish active in tropical and subtropical oceans. They are ferocious by nature and swim fast. When attacking a target, they c...

Silurus asotus

Silurus asotus

Silurus asotus,Amur catfish, mullet, catfish, catfish, mullet, croaker, croaker, yellow croaker

Features:The body is cylindrical and dark gray or grayish yellow, with a flat head, a large mouth and whiskers.

Catfish is commonly known as pond catfish, also called catfish, belonging to the genus Siluridae and the family Siluridae. It is a ferocious carnivorous fish. It has strong adaptability, lives on the bottom, swims slowly, tolerates low oxygen, and can survive below 1 mg/L. During the day, it rarely...

Parabramis pekinensis

Parabramis pekinensis

Parabramis pekinensis,Changchun bream, grass bream, oil bream, long-bodied bream, chaotou bream, shrink-necked bream

Features:The head is very small, the mouth is small, long and rhombus-shaped, and silver-gray.

Bream can grow in still water or flowing water, and generally swims and feeds in the middle and lower layers. In China, it is distributed in the plains from Heilongjiang to the Pearl River and Hainan Province, but not in the Tumen River, Yalu River, and above the Longmen of the Yellow River. Juvenil...

Coilia nasus

Coilia nasus

Coilia nasus,Bitter fish, anchovies, hair fish, razorfish, hairy fish

Features:The body of knife fish is narrow and thin, like a sharp knife, silvery white, tender, but with many fine hair-like spurs. The meat is delicious, fat but not greasy, and slightly fragrant.

Knife fish, scientifically known as long-jawed anchovy, also known as knife anchovy and hairy anchovy, is a migratory fish. Knife fish usually live in the sea. They enter the river from the sea in February and March every year and migrate upstream for reproduction. Every spring, knife fish swim upst...

Monopterus albus

Monopterus albus

Monopterus albusApodidae, Apodidae, Genus Swiftlet, eel, yellow eel, field eel, field eel, long fish, blood fish, tilapia, scaleless prince

Features:The body is slender and snake-shaped, scaleless, and yellowish-brown in color. The body color often varies with the environment in which it lives.

Yellow eel (scientific name: Monopterus albus): also known as eel. It is a tropical and warm temperate fish, a bottom-dwelling fish with strong adaptability. It lives at the bottom of the water body, mainly in muddy waters such as rice fields, lakes, ponds, rivers and ditches, and even in swamps, fl...

Epinephelusspp.

Epinephelusspp.

Epinephelusspp.,Dragon grouper, dragon grouper,

Features:It has a thick body and a large mouth, which makes it unsuitable for long-distance and fast swimming.

Grouper is the general name for fish of the subfamily Epinephelinae, belonging to the class Osteichthyes, the subclass Neopterygii, the order Acanthopterygii, the order Perciformes, the suborder Percoidei, and the family Serranidae. It is a large and medium-sized warm-water marine fish, widely distr...

Larimichthys

Larimichthys

Larimichthys,yellow croaker,Yellow croaker, yellow croaker, kingfish

Features:The body is nearly rectangular and laterally flattened, with golden yellow sides and ventral side.

Yellow croaker, Larimichthys (D. S. Jordan et Starks, 1905), also known as yellow croaker, is a general term for a genus of yellow croaker in the family Sciaenidae. It is found in the East China Sea. There are two hard stones in the fish head, called otoliths, so it is also called stonehead fish. Th...

Larimichthys polyactis

Larimichthys polyactis

Larimichthys polyactis,Small yellow croaker, plum, plum fish, small king fish, small fresh, small spring fish, small cucumber fish, thick scale fish, flower fish, big eye, ancient fish, yellow scale f

Features:It is similar to large yellow croaker, but the difference between large yellow croaker and this species is that the caudal peduncle is more than 3 times longer than its height.

Small yellow croaker is a warm-temperate bottom-dwelling schooling migratory fish. It usually inhabits soft mud or muddy sea areas, and its vertical movement phenomenon will enter the estuary area. It hates strong light and likes turbid water. It rises at dusk and descends at dawn. It often inhabits...

Larimichthys crocea

Larimichthys crocea

Larimichthys crocea,Yellow croaker, yellow croaker, cucumber fish, golden dragon, big fresh, golden dragon, red melon, sweet-scented osmanthus yellow croaker, king fish, large yellow croaker

Features:It is similar to small yellow croaker, the main difference is that the caudal peduncle is thicker and more than twice as long as its height.

Pseudosciaena crocea is a warm and humid nearshore migratory fish. It often lives in the middle and lower layers of water within 60 meters. It likes turbid waters. It often floats at dawn, dusk or high tide, and sinks during daytime and low tide. It has the habit of swarming. In the reproductive sea...

Channa argus

Channa argus

Channa argus,Snakehead、Northern Snakehead,Black fish, mullet, black stick, snakehead fish, mullet, cuttlefish, cuttlefish,

Features:There are seven star-shaped markings on the top of the head, and the head is relatively long and pointed, like a snake.

The snakehead is a bottom-dwelling carnivorous and ferocious fish. It usually likes to live in shallow waters with dense aquatic plants along the coast. It lurks in the aquatic plants and waits for the opportunity to hunt for food. Sometimes it swims in the upper layer of the water at night. The fry...

Aristichthys nobilis

Aristichthys nobilis

Aristichthys nobilis,bighead、bighead carp,Silver carp, bighead carp, soap carp, black carp, bighead carp, bighead carp, fathead carp, bighead carp, black carp, bighead carp, male fish, pine black

Features:

It lives in the middle and upper layers of the main streams of rivers, gentle river bays, lakes and reservoirs. Juveniles and immature individuals generally grow in lakes along the river and affiliated water bodies. When they reach sexual maturity, they go to the river to spawn. After spawning, most...

Hypophthalmichthys molitrix

Hypophthalmichthys molitrix

Hypophthalmichthys molitrix,Silvercarp、Chinese Schemer,Silver carp, silver carp, jumping silver carp, silver carp, whale, white bream, white-footed silver carp, foreign fathead, white leaf, white fath

Features:The nostrils are high, above the front edge of the eye. The eyes are small and located below the mid-axis of the head.

Silver carp generally inhabit the upper layer of the main stream of rivers and their affiliated water bodies. They are lively and good at jumping. The newly hatched fry drift with the water; the young fish can actively swim into the river bay or lake to feed. The spawning group begins to gather in m...

Mylopharyngodon piceus

Mylopharyngodon piceus

Mylopharyngodon piceus,Black carp,Black mackerel, blue carp, black carp, stream fish, black fish, black fish, snail fish, black fin

Features:The body is stout and nearly cylindrical, with a round abdomen and no abdominal ridges. The head is medium-sized and the back is wide.

The black carp is not as active as the grass carp, but it is much stronger than the grass carp. Black carp is a carnivorous fish. Its main food source is mollusks at the bottom of the water, especially snail meat, so it is also called snail green. Black carp also eats clams, mussels, shrimps, dragon...