How to properly perform a water change in a fish tank?

To properly perform a water change in a fish tank, follow these steps:

1. Prepare new water by treating it with a water conditioner to remove chlorine and other harmful chemicals.
2. Use a siphon to remove about 25-50 of the tank water, being careful not to disturb the substrate or decorations.
3. Clean the tank walls and decorations with an aquarium-safe brush or sponge.
4. Pour in the treated new water slowly to avoid shocking the fish.
5. Monitor the water parameters for a few days after the water change to ensure the fish are healthy.