You can't keep a scavenger in a koi jar. Koi is bigger than scavengers, and they all live underwater, so it will pose a certain threat to scavengers and even eat them. Moreover, they have different requirements for the environment. Koi is a wide-temperature fish, which can adapt to a wide range of temperatures, while scavengers are tropical fish, which must keep a high water temperature to raise well, otherwise they cannot survive.

1. Similar body shape: First of all, we should pay attention to the body shape of fish in polyculture. It is less difficult to mix fish with similar size, because they are similar, so they don't want to eat each other. As long as they are gentle and not easy to fight, it is safer to mix fish. If you bite every day, it will also cause certain losses.

2. Similar habits: Fish raised together should have similar habits. For example, their requirements for water temperature and ph, if they are all fish that like weak acidic or weak alkaline water quality, it is more convenient to adjust the water quality. If one likes weak acidity and the other likes weak alkalinity, no matter how to adjust, one party will always be unable to raise the state.

3. The fish tank should be large: In order to ensure that the fish will not fight when they are mixed, they must prepare enough space for activities, otherwise some fish have territorial awareness, especially during estrus, and it is easy to fight if they are too crowded.