There are many types and quantities of freshwater fish on the earth, and most of them are carp species, so this is the core. petnet learned that the carpids are divided into the following seven areas on the earth:

1. Australia: The boundaries include Australia, New Guinea, and the east of Siberias Island. Including large and small islands. There is no real freshwater carp species in the fauna in this area. The real freshwater fish is only lungfish, mainly the fish from the elixir water, such as perch, porcupine and mullet Etc., there are also some catfish distributions.

2. Madagascar: There is only one species of real freshwater catfish. The other species of the island that enter the fresh water through the ocean are mainly marine catfish and cichlids.

3. Neotropical zone: The boundary includes Central America and South America, and can be divided into two zones, one is in the south, where freshwater fish is very poor; the other is in northern South America and Central America, There are many species and genera. There are 9 families of catfish endemic to this area, 4 families of quasi-cyprinids endemic to this area, electric eels are also endemic to this area, and American lungfish is also produced.

4. African region: The fish in this region are similar to those in South America and India, and the fish in this region and South America share the family Characida (Cichlida. (Cyprinodontida and India share 3 families of Catfishes. Snakehead (Ophiocephalida. Echida, etc.); The unique fish in this area are olecras (Morrnyrida. Polyfin (Polypt. African lung) Fish, etc.

5. India: The boundaries include India, Southeast Asia, Java, Sumatra and Borneo. Many fish in this area are similar to those in Africa, so some people propose South America. Africa. India At the beginning of the Cretaceous period, it was united into one continent. The endemic species in this area are some catfish (the Oriental Region of the Amblycepida belongs to this region, part of the Oriental Region, Indochina and other regions, the southeastern part of the Yunnan-Guizhou Plateau), the South China Sea Islands and South China Asia Area (including Zhuhai, Hainan Island, Zhejiang, Fujian, and Taiwan)

6. Palaearctic Area: The boundary includes the Himalayas in Europe and Asia and the area north of the Yangtze River. This area is the most abundant freshwater fish, and carp There are many kinds of families, some catfish and a large number of carps in this area have gradually moved northward from India, through China, Russia, eastward to North America, and westward to Europe. All countries belong to the Central Asia and Asia part of this area, including Heilongjiang Subregion, Inner Mongolia subregion, Hetao subregion, and river plain subregion.

7. New North Region: The boundaries include Canada, the United States and Mexico. The common taxa in most of the Palaearctic Region and New North Region are pike and perch Family (Percida, Loachidae, Cyprinidae, etc., the endemic groups in this area include gar, bowfin, most of the nopals and Amiurida fish. The Oligocene period was once connected.