I bought my first fish yesterday from a local store along with a 3 gallon tank kit with a filter. I ran the filter all day yesterday but this morning he did not seem very happy and was staying in one corner of the tank so I decided to turn of the filter for a couple of hours. As soon as i turned it off my fish immediately began to move about the tank and seemed much happier. I was browsing some other websites to learn about nitrogen cycling and whatnot. Everyone was saying how important it is to have a filter and how ammonia and nitrite will build up if I don't have one. My question is can I have a healthy three gallon tank without a filter but while still performing routine water changes if I keep the bio load down to one betta?