So, I have always kept my adult bettas in 1 gallon bowls with weekly 100% water changes and they have done well. This summer, I had some kind of disease shoot through my population and killed all but one betta which never even got sick. So, I threw out everything I owned, upgraded my remaining betta to a 2.5 gallon tank and he continues to do well. In petco, I saw the baby betta massacre they had going on and bought the only two that were still living. I currently have them in a 2.5 gallon divided tank. It is heated. They are only the size of my fingernail right now. I know they will need to be upgraded to a bigger tank eventually. My question is - I was going to get a filter for the tank, but after reading these forums, I'm thinking that a filter might be way too strong from my babys. Should I just do 100% water changes, or will that be too stressful for them? The tank has a moss ball and 2 java ferns in it. Thanks.