In aquaculture, fish, shrimp and crabs are all aerobic organisms, and they are at the top of the aerobic biological chain in the RAS system. When the ecological balance point of the water body is out of balance, the first problem that appears is the bottom aerobic organisms. When the water quality is detected, the imbalance has already begun. When the fish show symptoms, it indicates that the water body has deteriorated to a certain extent. Anaerobes have begun to multiply in large numbers and create a water environment suitable for reproduction. Merely applying drugs to treat fish diseases will only cause The water environment deteriorated further, leading to subsequent mass deaths of fish. The RAS system broke the natural ecological balance from the very beginning. How to maintain a high-density aquaculture ecological balance point requires additional man-made measures, and the aquaculture density should be gradually increased, instead of putting fry in a way that far exceeds the biological capacity of the water body from the beginning. Aquaculture is a long-term investment. It is not simply that the investment cost can be recovered in a few years with ultra-high aquaculture density. If the relationship between the natural carrying capacity of the water body and the additional increase is not considered, the probability of failure is very high. Artificially creating an ecological circle suitable for fish, shrimp and crabs, new water bodies also need time for organisms to gradually appear on the scene. For example, the formation of nitrifying bacteria and denitrifying bacteria biofilms takes 2 weeks or more to gradually multiply to the extent that humans can feel through eyes or touch. . After all the creatures are on the stage, a new ecological balance point can be formed. Sometimes the water body is too thin, the beneficial microorganisms are too few, and the fish grow too slowly, and sometimes the water is too fat, the harmful microorganisms are too much, and the fish get sick. At this time, back and forth adjustment is needed to reach a stable ecological balance point. If the back and forth adjustment measures are improper, the water body will deteriorate rapidly, the ecological balance point will change too much, a large number of fish will die, and the loss will be even more serious. Water ecology is similar to the ecological environment in which we humans live. RAS farming is like crowding people in the car during the subway rush hour. If you live in such a space for a long time, as long as someone gets sick and quickly spreads to other people, each person will be affected by the degree of disease. If the medicine is sprayed into the space and the amount of medicine is diluted, people who are seriously ill will not be effective enough, but people who are not sick will be harmed; if the pills are fed, the virus has spread to other parts of the space, and people will be cured. However, the environment has not been properly managed. Repeated infections and illnesses are treated again. Viral germs become resistant to drugs, and finally there is no cure. This process is just like the problems faced by the aquaculture industry. When a fish is diseased, spray medicine or bait on the water body, the fish is swimming, and it is basically impossible to find and isolate in time in the water and to target the medicine. When the highly contagious germs and viruses appear in this micro-ecosystem, none of the fish inside are spared. It is worth noting that the filtering biochemical equipment in the RAS system connects the fish ponds through the water cycle, forming a relatively large aquatic ecosystem, not just a fish pond. When a certain fish pond ecology collapses, it will quickly affect other fish ponds. Therefore, biological safety must be considered in the configuration of filtration biochemical equipment, and the cost cannot be reduced blindly.