How to turn traditional fish tanks into ecological fish tanks

The structure and composition are enough to form a complete food chain, that is, producers, consumers and decomposers, that is to say, there are many kinds of organisms, and it is best to meet the predatory relationship in nature. There must also be a suitable living environment, such as light, temperature and so on. Specifically, in addition to artificial feeding, it is best to have more kinds of fish in the water tank (not too many, otherwise the space and oxygen supply may not be enough, depending on the size of your fish tank), and to meet the relationship between the big fish eat small fish, and then you can add some plants (algae or phytoplankton) to provide oxygen sources (oxygen tanks, etc.). ). It would be better if proper illumination can be given so that plants can provide dissolved oxygen. Change the water regularly (it is best to keep some raw water, about 1/3) and so on, and think of other supplements.