CATDOLL : CATDOLL:How many species of freshwater fish are there?

1. How many species of freshwater fish are there?

There are about 28,000 species of fish in the world (more than 26,000 species have been recorded), and about 10,700 species of freshwater fish.

2. There are few species of freshwater fish

The statistical results in different periods and different works vary greatly. There are approximately 6,000 species of freshwater fish in the world.

1. Cyclostomes: This type of fish is the most primitive fish-shaped vertebrate. The fish mouth does not have real upper and lower jaws, and the mouthparts form a suction cup. It lives a parasitic or semi-parasitic life. There is no real spine on the body, only a notochord. In terms of the period of evolution, cyclostomes were first discovered in the Middle Ordovician, and were most developed in the Silurian and Lower Devonian. They gradually became extinct in the Lower Devonian, and only a few species remain today. In my country's freshwater, only three species of lampreys live in the rivers from Heilongjiang to Liaohe in the northeast region.

2. Cartilaginous fish: Cartilaginous fish were discovered in the Upper Devonian period and were most developed in the Carboniferous period. They continued to evolve and became modern sharks and rays. The bones of this type of fish are all cartilaginous, the scales are small shield scales, and there are spiral valves in the intestines. This is a group of low-level true fish. Almost all living cartilaginous fish live in the ocean, and only a few species live in fresh water. Among them, red stingrays not only live in the ocean in large numbers, but also have a small group settled in the Zuojiang River of the Xijiang River system from Nanning to Longzhou in Guangxi, my country. From its evolutionary history, red stingrays are marine fish. According to paleogeological research, Guangxi was originally an ocean. Due to the orogenic movement of the earth's crust, at the end of the Pliocene of the Tertiary Period of the Cenozoic Era, when the sea water withdrew from Guangxi, they were sealed off and settled in inland waters.



3. Cartilaginous fish: This type of fish belongs to bony fish, but the skeleton system is cartilaginous. The scales on the body surface are primitive bony diamond-shaped scales, the tail fin is crooked, and the intestine has spiral valves. Primitive cartilaginous fish appeared in the Devonian period and lived on the earth for a long time. Most species became extinct in the Mesozoic era. The living sturgeons appeared in the Cretaceous period. There are not many species alive now, and they are only distributed in the high-latitude Arctic Ocean. There is one species of Acipenser and 8 species of 2 genera of Acipenser living in freshwater in my country.

4. Teleostei: These are common, true fishes, and the most abundant fishes in modern times. Among the 1,500 freshwater fishes in China, except for a few species (13), almost all of them are teleostei. The freshwater fishes in China are mainly Cypriniformes, especially Cyprinidae, which account for about half of the total. Among them, there are 1 family, 3 genera and 5 species in the Herringiformes, 6 families, 17 genera and 32 species in the Salmoniformes, 1 family, 1 genus and 2 species in the Anguilla, 6 families, 170 genera and 740 species in the Cypriniformes, 10 species, 27 genera and 110 species in the Siluriformes, 2 families, 3 genera and 4 species in the Medakariformes, 1 family, 1 genus and 4 species in the Gnaphalidae, 1 family, 1 genus and 1 species in the Gadidae, 1 family, 2 genera and 2 species in the Acanthidae, 1 family, 3 genera and 7 species in the Mugiliiformes, 1 family, 1 genus and 1 species in the Synbranchiformes, 12 families, 51 genera and 110 species in the Perciformes, 1 family, 4 genera and 8 species in the Scorpionniformes, 3 families, 3 genera and 5 species in the Pleuronectes, 1 family, 2 genera and 6 species in the Tetrapodiformes. The total number is 15 orders, 49 families and 1,037 species.



Teleostei appeared in the Jurassic period. In the Cretaceous period, ancient teleostei evolved into modern teleostei, and their morphological structure changed significantly. The upper and lower jaws of the skull were generally shortened. The upper jaw of advanced types was specialized into a toothless bone rod, and the teeth were concentrated on the premaxilla. The tail fin became a completely symmetrical tail or orthomorphic tail. The internal skeleton was highly ossified, and the odd and even fins showed a variety of shapes. The pelvic fins were often moved from the abdomen to close to the head, and the scales became very thin and round. The internal and external structures of teleostei have perfect aquatic adaptation structures. Starting from the Cretaceous period, they developed along many radiation adaptation routes, making them the inhabitants of all water bodies on the earth's surface.

3. What are the types of freshwater tropical fish ornamental fish?

There are so many! The famous ones include dragon fish, koi fish, parrot fish, and so on! There are various tetras that match the planted tank, and there are various breams that are as colorful as saltwater fish!

They are all very beautiful! I hope this can help you, please adopt it!

4. Thank you Master: What are the main varieties of freshwater fish and their preparation methods?

Freshwater fish supplies more than ten kinds of live fish, including grass carp, silver carp, crucian carp, carp, mullet, squid, sweet-scented osmanthus fish, grass carp and sea bass. Freshwater fish can generally be steamed or braised, or cooked according to your own taste and the characteristics of the fish.