Because the water in the tank is generally stagnant water, this kind of water is particularly easy to breed bacteria and microorganisms. At this time, fish farming can purify the water quality, and it can also confirm whether the water is safe by judging whether the fish can survive. This practice is a way used by some old people in rural areas to purify water and test water a long time ago, and now it is almost impossible to see this way.

In the past, the countryside ate water from a jar. At that time, old people would raise fish in fish tanks. So some people have doubts: if you raise fish in a water tank, the fish will defecate and pollute the water quality. Can I still drink? In fact, most of the water in the previous water tank came from the river and was not disinfected at all. So the water itself is not clean, so raising fish in the water tank can also eat bacteria and microorganisms in the water, and may also play a role in purifying water.

It is common to raise crucian carp in water tanks. If the crucian carp in the tank dies, it means that there is a big problem with the water quality in the tank, and all the water in the tank needs to be replaced. In addition to raising crucian carp, many people in the south will put a turtle in the well. The purpose of releasing turtles is actually to test whether the water quality of some wells is safe. In addition, the rural elderly think that raising fish animals in water tanks means more than a year, which has a good meaning. There are also some old people who will break the dishes at home and then put the pieces in the water tank, which means peace throughout the year.

Now that our living conditions have been greatly improved, people don't need to take water from the river. Now people drink sterilized tap water, so few people will raise fish in drinking tanks.