Eight floristic complexes of freshwater fishes in China

Nikolsky proposed the concept of floristic complex in "Fish of the Heilongjiang Basin" (1960). The fauna complex refers to a group of animals (fish) that have a common geographical origin, develop in the same geographical zone, and are adapted to the biotic and abiotic conditions of the zone within a specific period of time. Based on this concept, the fish fauna in the Heilongjiang Basin is divided into six fauna complexes, namely, the Chinese Plains Complex, the Ancient Tertiary Complex, the Northern Plains Complex, the Northern Mountain Complex, the Arctic Freshwater Complex, and the Indian Plains. Complex. This division of his had a great influence on subsequent research on Chinese fish zoogeography, and many works were conducted under this theoretical framework.

In 1985, Mr. Shi Weiliang published an article in "Aquatic Science" proposing his views on the fish fauna complex. He believed that China's freshwater fishes are mainly composed of eight fauna complexes. The characteristics of these fauna complexes are: :

1. China Plains Floral Complex: This fauna is composed of herring, grass carp, silver carp, bighead carp, bream, bream, bream, red bream, pommel, horsemouth, bream, snakehead catfish, and snout. The representative species include catfish, catfish, white catfish, catfish-like catfish, barbeled catfish, catfish, red-eyed trout, catfish, catfish, and catfish. The characteristics of these fish are: a large number of them lay drifting eggs, and some fish lay sticky eggs, but the stickiness is not very strong. After the eggs are laid, they are attached to the object and then detach soon, and develop by drifting with the water. The fishes in this complex are all sensitive to water level changes. Many species enter the rivers from lakes to spawn when the water level rises. Young fish and broodstock that have spawned eggs enter the lakes in autumn for fattening. In the north, when water levels drop in late autumn, fish return to rivers to overwinter. Many species have a simple diet and can adapt to higher temperatures.

The fishes of this complex appeared relatively late in geological history, and the earliest strata discovered were the Pliocene. They were formed after the Himalayas rose to a certain height and formed the current typical East Asian monsoon climate in my country. In order to adapt to the new natural conditions, they evolved from Differentiated from old types of fish. The origin center of this type of fish may be in the Central Plains area. The fish in the China Plain Complex did not have the opportunity to spread far away due to their late origin. When the sea retreated, they reached the Korean Peninsula and Japan. They did not exceed Heilongjiang to the north, to the Red River to the south, and to the west due to temperature restrictions, it was difficult to exceed one Mountains above 1,000 meters. Therefore, it can be considered that some large fish that lay drifting eggs are specialties of my country.

2. Southern Plains Floral Complex: Representative species include snakehead catfish, catfish, eel, medaka, spiny loach, bearded catfish, dace, mud carp, etc. This type of fish is often grass-colored and has many patterns on its body. Some species have spines and accessory respiratory organs to absorb free oxygen. This type of fish likes warm water, breeds in summer when the water temperature is higher, and often has the habit of protecting eggs and young. In East Asia, there are more species toward lower latitudes. Distributed to Southeast Asia, with a few species reaching India. This type of fish is suitable for living in shallow lakes and ponds with hot climates and many water plants that are prone to hypoxia.

The fish in this complex originated earlier, and fossils have been found in the Miocene strata of my country. Its distribution is bounded by Heilongjiang in the north, across a plateau no more than a kilometer away in the west, and as far as North Korea and Japan in the east.

3. Southern Mountain Area System Complex: The species in this complex include Loachidae, Trichodermaidae, and Trichodermaidae. This type of fish has specialized adsorption structures and is adapted to living in rapid rivers in southern mountainous areas. Distributed in the mountainous areas of southern my country and mountainous rivers in Southeast Asia.

4. Central Asian Mountain System Complex: The species in this complex include all species of the Schizothorax subfamily and some species of the Schizothorax subfamily. It is characterized by cold resistance, alkali resistance, late sexual maturity, slow growth, miscellaneous feeding habits, and its gonads are toxic. It is a fish unique to the alpine zones of Central Asia. Distributed in my country's western plateau Xinjiang and adjacent western areas such as India, Pakistan, Afghanistan, Tajikistan, etc., it is a species that differentiated from the fish subfamily Barbelinae with the uplift of the Himalayas.

5. Northern Plains Floral Complex: The representative species of this complex include catfish, pike, yarrow, silver crucian carp, lake bream, etc. They are cold tolerant, relatively salt-alkali tolerant, and have an early spawning season. It occurs lower in the stratigraphy than the China Plain Complex and is widely distributed at high latitudes. The number and population of this complex gradually decreases with decreasing latitude.

6. Early Late Tertiary faunal complex: Its representative species include lamprey, catfish, catfish, catfish, catfish, catfish, catfish and six-bearded catfish. These fish are remnants of subtropical animals in the northern hemisphere before the Pleistocene. Due to climate cooling, the fauna complex was divided into several discontinuous areas. Some species coexisted in Eurasia, but have become extinct in Siberia, so these fish Considered a relic species. Their common characteristics are underdeveloped vision and developed sense of smell. They mostly feed on benthic organisms and are adapted to life in turbid water.

7. Northern mountain area system complex: This complex includes slender fish, slugfish, grayling, eelfish, sculpin, etc. Most of these fish are spindle-shaped, with darker backs, black spots on the sides, and silvery white abdomens. They swim quickly, eat a certain proportion of aerial insects, and like to live in low-water-temperature rivers flowing in mountainous areas. These fish originated earlier and are widely distributed, reaching as far south as the Yellow River and Luanhe River systems and the northern tributaries of the upper reaches of the Yangtze River. In high latitudes, some rivers in northern Xinjiang, Mongolia, and the Russian Arctic Ocean water system are distributed. Its closely related species can be found in Europe and America.

8. Arctic freshwater flora complex: Its representative species include whitefish, char, burbot, etc. This type of fish is cold-resistant and requires low temperatures for spawning. Some species live in still water and still feed in winter. They are some ecological types of fish that live around the Arctic Circle. There are more related species in Europe and North America, especially burbot. It is widespread and can be found in Europe, Asia and America. This type of fish originated earlier and is widely distributed.

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