1) is classified by salt concentration in water?

The most commonly used classification:

Primary freshwater fish; Fish that can only live in fresh water all their lives. It accounts for 33. 1% of the total fish in the world, with about 8600 species. For example: catfish, arhat fish.

Secondary freshwater fish; Fish that live in fresh water most of the time and occasionally move or inhabit salt water and seawater. It accounts for 8. 1% of the total fish in the world, about 2 100 species. For example: Wu Guoyu, pot-bellied fish.

Peripheral freshwater fish; Fish that inhabit seawater or salt water will also live in fresh water or migrate to salt water. Including upstream fish, downstream fish and marine fish that occasionally enter rivers. It accounts for 0.6% of the total fish in the world, about 160 species. For example: snake eel, oxtail fish.

Second, classification? fold

Salmon (spawning upstream) pure freshwater fish; Fish that have lived in fresh water all their lives. For example: catfish, arhat fish.

During my career, I lived in fresh water, ocean and other waters with different salinities for some time. Include anadromous fish and downgoing fish. Sealed migratory fish on land geographically isolated from the sea. For example: salmon, fragrant fish.

Third, it can be divided into two categories: freshwater migratory fish and river and sea migratory fish.

Freshwater migratory fish; The life history of freshwater fish, including migration, is carried out in fresh water. For example: China rock climbing loach in Puli.

River and sea migratory fish; In its life history, it will pass through habitats with different salinities. The intersection of rivers and oceans is the only place for their migration. For example: Japanese bald shark.

Estuary fish; All the fish that live at the intersection of salt water and sea water. For example: brown pond fish.

Four, China freshwater fish according to what classification? fold

Round mouth class; The most primitive fish-shaped vertebrate. The fish mouth has no real upper and lower jaws, and the mouthparts are sucker-shaped, mostly parasitic or semi-parasitic animals. There is no spine, only the notochord.

Softwood fish

Lower fish. Bones are all cartilage, scales are small peltate scales, and there are spiral valves in the intestine.

Chondroscleroderma fish

Bony fish The skeletal system is cartilaginous, the original scale is rhombic, the caudal fin is curved, and there are spiral valves in the intestine.

Bone fish. The most common, abundant and prosperous fish in modern times.

Among the 1050 species of freshwater fish in China, except for a few 13 species, the rest are true bone fish. ?

Verb (abbreviation for verb) living habits

Bamboo shell fish is a kind of benthic cave fish, which often inhabits rivers and waters with clear or flowing water quality. Sand shrimp and tiger fish

Bamboo shell fish; The bottoms of reservoirs and ponds are covered with sand, mud or grass, and often inhabit cracks, caves and sundries on the shore. Swimming ability is not strong, swimming is not fast, and you can't swim far. Mild, adapted to low oxygen environment. Most of them are active at night and like to hide in the mud during the day. The optimum temperature range is 15-35℃, the optimum temperature is 25-30℃, and a large number of people die below 10℃. It can adapt to acidic water with pH value of 5 and 1.5‰ salty fresh water. It is difficult to catch it in nature. ?

Bamboo shell fish is a freshwater fish, and its culture temperature range is 15-33 degrees, the suitable temperature is 25-30 degrees, and the lower limit temperature is? 10℃, the upper limit temperature is 37℃, and the suitable PH value and acidic salinity of water are 7-8.5. It can grow in acidic water with PH of 6.5 and salty fresh water with salinity of 10%. ? It is a carnivorous, benthic, cave-loving fish, afraid of light, and prefers to hide in crevices and caves rather than swim. Compared with other carnivorous fish such as raw fish, mullet and mandarin fish, its nature is not fierce. Usually just stay quietly in the water, only when food (small fish, shrimp) swims near it will become fierce, and when fishing, it will become very flexible and can quickly chase prey. ?