1, water temperature and water quality problems. The water temperature is generally constant, so there is no problem. This kind of fish has the function of self-purification. As long as it is not particularly mixed, the problem is not big. Generally, it is enough to change the backwater once every three months. Ordinary fish don't need light and heat.
2, environmental factors, the most basic thing is the problem of water, sometimes because of the sudden change of weather, the temperature drops, then the water temperature suddenly drops, which easily leads to fish can not stand it. At the same time, there is water quality, which means that everyone should remember to change the water in time.
3, biological factors, generally speaking, fish are attached to various bacteria or algae when they are bought back, and some biological factors harmful to fish can easily lead to fish death.
4, the problem of the fish itself, like age. Just like people, when fish reach a certain age, their resistance will decline, so they are more likely to get sick, which requires more care from their friends.
5, man-made, such as fish hypoxia caused by power failure in the fish tank, or accidental injury to fish when changing water, leading to bacterial invasion, are often encountered.
It is the characteristic and core of pond culture technology in China to cultivate different fish of the same age, the same age and different specifications with different habitats and different feeding habits in the same water body. Mixed fish farming should be habit-related, and the requirements for water quality and water temperature are similar (in the growth period). The ideal fish for polyculture are silver carp, bighead carp (pelagic fish), grass carp, snakehead (pelagic fish), carp, crucian carp, shad and herring (pelagic fish).
Mixed culture of fish living in different water layers can make three-dimensional use of water space. Compared with monoculture, it can greatly increase the density of fish. The excrement of grass carp and herring is not only a fertilizer for cultivating plankton, but also provides a lot of organic debris and reproductive flora for silver carp and bighead carp to filter. Carp, herring and crucian carp can remove residual bait and improve water quality.
It not only makes full use of the water body, improves the yield, but also recovers the bait and improves the water quality. Mixed culture of the same species of fish with different ages and specifications also provides conditions for batch fishing and balanced listing in one production season, and also cultivates large-scale fish species for the next year.
Mixed fish culture should be divided into primary and secondary, and main fish culture is the main object of feeding and feeding management. Fish matching plays a role in making full use of water and reusing bait. There are four types of polyculture in pond culture in China.
References:
Baidu encyclopedia-pond culture