There are many marine animals and plants living in natural seawater, such as plankton, microorganisms, insects and fungi. These insect plankton in the ocean due to wave tide and wind and rain impact, sun exposure, oxygen content, water pressure, substrate and other reasons. Coupled with the food chain of fish creatures, various factors interact to change the marine environment. Changes in the environment may cause the death of living things, and some may cause the living things to change and multiply. The cycle repeats to keep the ocean always in ecological balance.

But after putting the natural seawater in the aquarium tank. Because there is a good environment for living creatures, many predatory natural enemies are eliminated, so many harmful bacteria will multiply in large numbers and occupy the entire aquarium tank. An attack on the fish body resulted in the death of the coral reef fish. Therefore, natural seawater must be treated before it can be used.