I have taken a pair of blue gouramis and put them into a small betta tank so that they could breed, and I could get her out afterwards easier, and the bubble nest would not be disturbed by the other fish. Do they do that?? Anyway, I have a heater in there, so I know the temp is good, and I have aeration (very light bubbles) and he has begun building a bubble nest and she is looking "puffy". I have separated the tank until she is ready, because he has begun to nip at her fins and she appears miserable although they get quite chummy other times. OK. Here's my question. I do not have a filter, I thought I could just do water changes every few days and it would be ok. Well now I'm wondering how I'm going to do that without disturbing the bubble nest. (Duh) I have a 40 gal tank, and didn't really want to buy an expensive filter for this little betta tank if I didn't have too..Any suggestions, or do I just bite the bullet and buy a filter?