So I have a 30L (Clear Seal) tank and was thinking I could get a heater and put a single betta in there? Is this tank big enough (I did really want an angelfish but I know this tank is too small) and also I don't know anything about bettas (the LFS sells them as 'fighting fish') so please tell me EVERYTHING I need to know about keeping bettas and whether or not they make a good pet! Thank you!!