The most suitable water temperature for koi fish is between 20-27 ℃. Although koi is a wide-temperature fish, it still prefers warm environment. If the temperature is too low, it will also affect its vitality. Usually, it can survive in an environment of 5-30 ℃. If the water surface freezes, it will not freeze to death as long as the underwater temperature is suitable. Although there is no need to prepare heating rods for artificial breeding, attention should be paid to temperature control in winter to avoid too large temperature difference between day and night.

1. Goldfish: Goldfish is one of the common ornamental fish, which has a long history of cultivation in China. It is not only numerous in variety, but also rich in color. Generally, goldfish are divided into four categories, namely grass species, culture species, dragon species and egg species, among which grass species are the best to raise, while egg species are relatively difficult to raise.

2, Guanbei Medaka: Guanbei Medaka is a small ornamental fish cultivated in modern times. Compared with common small tropical fish, its best advantage is that it does not need heating and has strong adaptability. Its body length is about 3-6 cm, living in the life layer of water body, and its nature is mild.

3. Myxocyprinus asiaticus: Myxocyprinus asiaticus is about 15 cm long and belongs to large freshwater fish, which lives in the middle and lower layers of water and mostly feeds on invertebrates. This kind of fish is mainly distributed in the Yangtze River basin of China, with a large number in the upper reaches.