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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
Pleuronectiformes

Pleuronectiformes

Pleuronectiformes,heterosomata,flounder

Features:

Flounder is a general term for fishes of the order Plaice. It has no swim bladder and feeds on worms, crustaceans and other animals. Taxonomically it belongs to the class Actinopterygii, Pleuronichthys. The flatfish has a flat body with eyes that grow on only one side of the body, a unique asymmetri...

Cyprinus carpio

Cyprinus carpio

Cyprinus carpio

Features:Physical fitness, colorful, changeable pattern, swimming style

Koi (Cyprinus carpio haematopterus) is a kind of high-grade ornamental fish popular in the world today, and has the reputation of "living gems in the water" and "art that can swim".Koi is an omnivorous fish. It can be eaten by mollusks, fragments of higher aquatic plants, benthic...

Tetraodontidae

Tetraodontidae

Tetraodontidae,pufferfish、puffers,Pufferfish, boatfish, pufferfish, good fish, chicken, turtle fish

Features:When angry, it turns into a balloon. It is the most poisonous fish.

Pufferfish (scientific name Tetraodontidae) is also known as pufferfish or puffers in foreign languages. Because of its "pig-like" appearance and its frequent activities in river estuaries, it is commonly known as pufferfish in Jiangsu and Zhejiang, while it is called Dingba in Shandong, L...

Eleginus gracilis

Eleginus gracilis

Eleginus gracilis,cod, bighead cod, bighead fish, bighead fish, pollack

Features:Known as "gold in the sea" and "nutritionist on the table" in Europe

The scientific name of cod is Eleginus gracilis. It is a kind of deep-sea fish and one of the economic edible fish. There are 9 species, namely: silver cod, Pacific cod, Atlantic cod, haddock, blue cod, green cod, haddock, Norwegian cod, and pollock.Cod is a cold-water fish in the middle and lower l...

Psychrolutes marcidus

Psychrolutes marcidus

Psychrolutes marcidus,Blobfish,Sad fish, soft-spined sculpin, popper fish

Features:The saddest fish in the world

The Latin name of the blobfish is Psychrolutes marcidus, and its foreign name is Blobfish. It is also known as the sad fish, soft hidden sculpin fish, and popper fish. Because it has a sad face, it is called the "sadest expression fish in the world".In order to protect endangered ugly anim...

Danionella dracula

Danionella dracula

Danionella dracula,Toothpick fish

Features:It is named after the vampire in European legend.

The scientific name of the vampire fish is "Danionella dracula", a small carp found in Myanmar. It is estimated that it has been bred on Earth for nearly 100 million years. Because of its sharp teeth and terrifying appearance, it is similar to the vampire in European legends, so it is nick...

Mitsukurinidae owstoni

Mitsukurinidae owstoni

Mitsukurinidae owstoni,Goblin shark, Goblin shark, Goblin shark

Features:The snout protrudes forward to form a sharp protrusion, which will explode

Owstoni's sharpnose shark (scientific name: Mitsukurinidae owstoni), also known as Owstoni's sharpnose shark, Owstoni's sharpnose shark, sharpnose shark, goblin shark (goblin is an ugly monster in Western folklore that likes to play pranks), is the only species under the family of sharpn...

Lophiomus setigerus

Lophiomus setigerus

Lophiomus setigerus,black-mouth goosefish,Blackmouth anglerfish, stutter fish, anglerfish, toadfish, old man fish

Features:Very similar to the yellow anglerfish, but smaller than the yellow anglerfish

The Latin name of black anglerfish is Lophiomus setigerus (Vahl, 1797), and its foreign name is black-mouth goosefish. There are only two kinds of anglerfish in China, one is called yellow anglerfish and the other is black anglerfish.It grows in the depths of the dark sea, moves slowly, and does not...

Lophius litulon

Lophius litulon

Lophius litulon,Toadfish, stutterfish, sea turtle

Features:Looks indulgent, swims slowly, comes with its own fishing rod

Yellow anglerfish, whose scientific name is Lophius litulon, is a deep-sea benthic fish.Yellow anglerfish usually lures prey with its snout tentacles and bait balls, sucks the prey in one gulp, and feeds on fish and crustaceans. The main prey of yellow anglerfish in the southern Yellow Sea are small...

Trachidermus fasciatus

Trachidermus fasciatus

Trachidermus fasciatus,Four-gilled perch, flower drum fish, wife fish

Features:Looks like a tadpole

Songjiang perch (scientific name: Trachidermus fasciatus) is a fish of the family Sculpinidae and the genus Trachidermus, with no subspecies.Because the production of Songjiang near the mouth of the Yangtze River in China is relatively high and the body is relatively black, it is named Songjiang per...

Cheilinus undulatus

Cheilinus undulatus

Cheilinus undulatus,Giant Wrasse,Napoleon wrasse, wavy parrotfish, curved lip fish, Napoleon bream, dragon king bream, sea bream, big piece

Features:It is a high-end edible fish and the largest coral fish in existence. It has a unique appearance and is therefore also a high-end ornamental fish.

Cheilinus undulatus (scientific name: Giant Wrasse) is a large wrasse with no subspecies.Cheilinus undulatus is usually solitary, but may sometimes appear in pairs. Adult fish cruise between reefs during the day and live in reef caves and under coral shelves at night. Although the rippled lip fish i...

Bahaba taipingensis

Bahaba taipingensis

Bahaba taipingensis,Chinese Bahaba,Golden money sturgeon, golden money croaker, golden money fierce fish, fish high, big gull, white flower fish, yellow sweet

Features:The tail peduncle is slender, the snout is prominent, the dorsal side of the body is gray-brown with orange-yellow, and the ventral side is gray-white

Chinese Bahaba (scientific name: Bahaba taipingensis) is called Chinese Bahaba in foreign language. It has no subspecies and belongs to the family Sciaenidae and the genus Bahaba.Chinese Bahaba gathers in clear water and disperses in turbid water. Juvenile fish live in estuaries and nearby coasts. D...

Dwarf Seahorse

Dwarf Seahorse

Hippocampus zosterae,Dwarf Seahorse

Features:The small seahorse is one of the most popular seahorses in the aquarium trade, and once ranked second in the top ten fish exported from the aquarium trade in Florida (Wood 2001).

The dwarf seahorse is the smallest of the Syngnathidae and Hippocampus.The diet of the dwarf seahorse consists of live prey, including small crustaceans such as amphipods, shrimps, other small invertebrates and fish fry. When foraging, they sit in a position secured by their tails and wait for prey...

White’s seahorse

White’s seahorse

Hippocampus whitei,White’s seahorse

Features:In ancient Greek mythology, the hippocampus was the mount of Poseidon, the god of the sea.

White’s seahorse is a species of Syngnathidae in the order Acanthopterygii of the class Actinopterygii.White’s seahorse is carnivorous, feeds on small crustaceans, and is ovoviviparous.The reproduction method of the White Seahorse is very special. First of all, the reproduction of the White Seahor...

Hippocampus waleananus

Hippocampus waleananus

Hippocampus waleananus,Wari Island Dwarf Seahorse

Features:Named after the Indonesian island of Wari where it was discovered

Warren's pygmy seahorse, Hippocampus waleananus (M. F. Gomon et Kuiter, 2009), is an animal of the genus Hippocampus in the family Syngnathidae.The genus Warren's pygmy seahorse is carnivorous, feeding on small crustaceans and giving birth to live young. The seahorse was first described in 2...

Hedgehog Seahorse

Hedgehog Seahorse

Hedgehog Seahorse,Hippocampus spinosissimus

Features:The spiny seahorse is a small fish that can be used for academic research and aquarium viewing, and can also be made into a Chinese medicine.

Hedgehog Seahorse is a fish of the Syngnathidae family and the genus Hippocampus.Hedgehog Seahorse mainly feeds on small crustaceans and other planktonic invertebrates. Hedgehog Seahorse is oviparous. During reproduction, the female uses an ovipositor to transfer the eggs to a brood pouch under the...

Hippocampus sindonis

Hippocampus sindonis

Hippocampus sindonis,Sindo's Seahorse,Moss Seahorse,hana tatsu

Features:The colors vary, and each ring has a tumor or thorn

The Latin scientific name of the flower seahorse Hippocampus sindonis, and the English name Sindo's Seahorse comes from the name of M. Sindo, the assistant curator of fish at Stanford University, and was coined by Kuiter in 2009. The Japanese name hana tatsu literally means hana (flower or flowe...

Japanese Seahorse

Japanese Seahorse

Hippocampus mohnikei,Japanese Seahorse

Features:The body is very small, flattened laterally, with a protruding abdomen and a well-developed dorsal fin.

Japanese Seahorse is called Japanese Seahorse in English. It is an animal of the Syngnathidae family and the genus Hippocampus.The Japanese seahorse is a warm-temperate fish that prefers to live in coastal areas with gravel bottoms. It is commonly found in seaweed patches from mid-tide to low-tide a...

Hippocampus kuda

Hippocampus kuda

Hippocampus kuda,Spotted Seahorse,Kuda Seahorse

Features:The seahorse is the largest and most valuable species of seahorse, and is also one of the finest species for artificial breeding.

Hippocampus kuda (scientific name: Hippocampus kuda), also known as Spotted Seahorse in foreign language, is an animal of Syngnathidae and genus Hippocampus.Pipe seahorses often live in coastal bays, ports and lagoons, sandy sediments in rocky coastal areas, large algae and seagrass beds, mangroves,...

Hippocampus kelloggi

Hippocampus kelloggi

Hippocampus kelloggi,Kelloggi'sseahorse,Seahorse, Grimm's seahorse, Ryukyu seahorse, seahorse

Features:The male fish has a brood pouch on the ventral surface of the tail, and its body is dark gray or light yellow, with irregular white linear spots or stripes on the sides of the body.

Kelloggi's seahorse (scientific name: Hippocampus kelloggi), foreign name Kelloggi's seahorse, is a Syngnathidae, Hippocampus.Kelloggi's seahorse is a warm-water fish near the coast. They like to live on the seabed gravels or algae in coastal areas and inner bays, where there is little f...

Hippocampus jayakari

Hippocampus jayakari

Hippocampus jayakari

Features:Greedy, males have pouches

Jia's seahorse, Latin name Hippocampus jayakari, is a species of Syngnathidae in the order Acanthopterygii of the class Actinopterygii.Although it looks gentle, the Chiari seahorse is a voracious carnivore that eats any animal it can swallow, mainly small crustaceans, fish and other invertebrate...