Why does the little goldfish always stay by the fish tank and not swim?

Need to judge first, there may be two reasons and their solutions:

The fish got sick and got white spot disease. In the morning, the original salt was added to the fish tank, and in the afternoon, a third of the water was changed, so for three consecutive days. Three days later, potassium permanganate was added to the bathtub for sterilization. Finally, oxytetracycline is added. If there is a heating rod, the water temperature should be controlled at about 30℃.

The water quality is turbid. Perhaps because it is a new fish, it is still relatively unfamiliar to the environment. Usually, you shouldn't be disturbed. There should be plenty of oxygen and the lights can be dimmed. In order to let them rest, let them return to normal after a period of time.