I have 9 tanks, but only 3 are in use atm. Got a custom 13 gallon, custom 8 gallon, and a standard 5 gallon. All Bettas. My one year old boy is in the 13 gallon, 2 year old boy is in the 8 gallon, and my 2 year old girl is in the 5 gallon. Beyond those and the hospital tank, nothing is setup. Both of my 4 year old boys passed away recently so I'm not too keen on getting more right this second.