The reasons why goldfish swim upside down:

1. The temperature difference is too large. When the water temperature suddenly changes, goldfish will be stimulated, causing them to stand upside down.

2. The water level is too shallow. Although goldfish do not have high requirements for water level, if the water level is too shallow, it will cause them to stand upside down.

3. Overfeeding. When food accumulates in the intestines and stomach, flatulence is likely to occur. If there is too much gas in the intestines and stomach, they will appear upside down.

4. Swim bladder loss. There are many reasons why goldfish suffer from swim bladder loss, such as internal organ injury, internal inflammation, swim bladder injury, etc.

Solutions for goldfish swimming upside down:

1. Keep the water temperature. A heating rod needs to be installed to keep the water temperature within a stable range. As long as the water temperature remains within a stable range, their inversion can be alleviated.

2. Raise the water level. First raise the water level to about 30 centimeters. After they adapt to the new environment, the inversion situation can be alleviated.

3. Stop feeding. This can alleviate the situation of overeating and increase the water temperature to keep it at around 28°C. High temperatures can increase the metabolism of goldfish and speed up their recovery.

4. Medicinal bath. The breeder will need to create a splint first to restore their normal balance. Then use yellow powder or oxytetracycline to give the sick fish a medicated bath. After 1 week of continuous medicated bath, the swim bladder loss can be restored.