I have two active tanks. One ten gallon tank has one Betta Splendens. The other one is a 40 gallon breeder and has 8 small fish. 3 neons, 2 corries,1 zebra and 2 male guppies. My water changes are as following. The 10 gal gets a 20% change once every 4 weeks, and the 40 gal tank about 8% every week, and sometimes twice. I had a site which gave stocking and WC advice but my computer crashed and I lost it. If anyone knows which site I am referring to, I would appreciate a link. I also am interested on exchanging posts with Betta owners who are serious Betta keepers with lots of experiences with them. I am not interested in breeding.