While it's generally a good idea to get a big tank to give fish plenty of room to swim about, some species like the Betta need less water than others. The minimum amount of recommended water for these colorful creatures is one-gallon-per-one-inch of fish. Keep in mind that, if you are keeping your Betta in a small tank or bowl (especially one without a tank or filter), you will need to change the water every few days while adjusting it to room temperature before adding fish. To see some sweet fishbowls and get started with a new friend, read more.
Dec 17 2007