It is better to raise goldfish, koi fish, white cloud golden silk fish, medaka and sole catfish in the water tank. These fish are wide-temperature fish, so the water tank cannot be equipped with heating rods, so it is not suitable for raising tropical fish, and only some fish with strong adaptability to water temperature can be raised. In addition, limited to the way of viewing, it is recommended to raise goldfish, koi fish and medaka, all of which are enjoyed from above.

1. Change water: First of all, pay attention to changing water when raising fish in open water tank. Usually, there is no fixed period for changing water, and it needs to be changed once every three to seven days. It is more difficult to maintain the water quality of open-air water tanks, so it is necessary to change water in time to ensure the cleanliness of water bodies. Every time you change water, you only need to change one fifth of the total amount, so there is no need to change too much.

2. Oxygenation: Although the water tank is open-air and has full contact with the air, if there are more fish or their bodies are relatively large, it is easy to suffer from hypoxia, which will lead to fish floating. Therefore, it is best to use an air pump to pump oxygen into the fish tank, so as to ensure sufficient oxygen in the water.

3. Avoid light: Because the water tank is open, it is easy for algae to enter. Under long-term illumination, algae will multiply in large numbers, which will affect the overall environment and even lead to the death of a large number of fish. Therefore, for the health of fish, it is best to avoid light properly, and the time of illumination should not be too long every day, so as to prevent temperature changes.