Fish water should be filtered and oxygenated to be good. The function of filtration is to maintain water quality. Because fish eat and excrete in water, the water quality will be affected to some extent, and it will deteriorate over time, which is harmful to the health of fish. Filtration can filter out impurities in water, adsorb harmful ions, and transform ammonia nitrogen. As for oxygenation, the main purpose is to increase dissolved oxygen to facilitate respiration, and to promote the establishment of nitrification system.

1. Water quality: First of all, we should pay attention to water quality in fish farming. Besides filtration, the most important way to maintain water quality is to change water. Usually, water should be changed once a week, and if the filtration is better, it can be changed once every two weeks. Every time you change water, you need to change one quarter or one fifth. Too little will not work, and too much will stimulate fish.

2. Water temperature: Fish, as a temperature-changing animal, has high requirements on temperature, and usually keeps the temperature constant, and the temperature difference between day and night is preferably lower than 2 ℃. If it is tropical fish, it also has certain requirements for low temperature. The lowest temperature should not be lower than 20 ℃, preferably around 22-24 ℃.

3. Dissolved oxygen: Because fish need to breathe in water, the level of dissolved oxygen is particularly critical. Usually, oxygen pump should be used for oxygenation. If the fish tank is small and the fish's demand for oxygen is not high, oxygen can also be supplemented by changing water.