I would like to add some more information:

No, you do not need a heater and you do not need a filter. I would put gravel or stones on the bottom. Change the water once a month, but do not change with tap water. I would let it sit overnight and put in chlorene remover. Letting the water sit overnight would let the temperature of the water get to room temperature. If you must use tap water, only use cold water, never hot water. If possible when changing, use bottled water from the store. That is your best bet, because it has no harmful chemicals at all.

Tom