Tap water usually needs treatment
Bettas should not be placed directly into untreated tap water. Many municipal water supplies contain chlorine or chloramine, which can harm fish and beneficial bacteria.
Use water conditioner
Use an aquarium water conditioner that treats chlorine and chloramine according to the label. Add it before the water goes into the tank or as directed by the product.
Match temperature
Conditioned tap water should also be close to the tank temperature before a water change. Sudden temperature changes can stress a betta even when the water has been dechlorinated.
Test the tank, not just the tap
Tap water chemistry can affect pH, hardness, and nitrate, but the aquarium itself can still develop ammonia or nitrite. Use a test kit to monitor the tank after setup and water changes.
Avoid risky shortcuts
Letting water sit out may reduce chlorine in some cases, but it is not a reliable solution for chloramine. A proper conditioner is the safer beginner choice.
