Cleaning Your Betta Tank
One of the most crucial things you can do to maintain a healthy and happy pet Betta fish is to keep its tank... as clean as possible.
If you're keeping your Betta fish in say a small bowl without any type of filtration system (or, you've put your Betta fish in a container or tank over one gallon) you should at the very least change 25 to 30 percent of its water at least once a week.
If your Betta is in a much smaller tank or bowl you should change all of its water 3 to 7 times a week!
It's practically impossible to change the Bettas water too often in a bowl of smaller size. Remove any debris, excrement or uneaten food particles immediately after feedings.
How To clean Your Tank Or Bowl
Note: It's also a good idea to use some boiling water. But make sure that your wear thick rubber gloves so that you don't scold yourself.