How do you change water for goldfish?

Changing goldfish water can follow these steps: First, prepare the replacement water in advance; if using tap water, let it stand for at least 2 days to remove chlorine. Second, make sure the new water’s temperature is close to the tank water, with a difference no greater than 2-3°C, to avoid illness from a large temperature swing. Then use a siphon to draw water from the bottom of the tank, which removes debris such as fish waste, leftover food, and dead algae settled at the bottom. Finally, add the prepared new water slowly along the tank wall, changing about 1/3 to 1/4 of the water.