coffee mugs are widely available, and are a very good alternative to a cave or decoration. they provide ideal hiding pots for the betta to feel more secure, which would leave them less prine to diseases. so if you dont have any toe of cave/decoration in the tank. a coffe mug can be used. as long a the mug wont leak any harmful substances, or ink into the water. there should be no adverse effect. but you will notice a positive difference in hbehaviour when you add a new hiding spot
Last edited by Mo; 04-15-2012 at 08:57 AM.