Well I would NEVER think of putting any type of gold fish in it. They are extremely nasty fish. Not a good "household" pet. They belong out doors in a pond. Yes I do have quite a few tanks....Lets see, I have a 75 gallon reef tank w/30 gallon refugium, a 29 gallon Euro tank with live rock and fish only, another 29 gallon tall natural tank with Angel fish and tetra's, 1 10 gallon freshwater tanks with neons, a few male only fancy guppies. 1 10 gallon with a natural bottom with freshwater clams and snails. Then there is my 20 gallon species only seahorse tank. Oh and the 55 gallon Oscar tank. Talking about nasty fish...Oscars are the worst ever! I love my guys but man their tank can get nasty quick. I have a 30 gallon hospital tank for both marine and fresh water tanks. All of my tanks are self sufficient and only require filter changes once every 2 weeks. I plan on keeping a betta only or a few Glofish in the Toilet tank aquarium. I could possibly get away with 3-5 of the Glofish and I can always remove them if its too many. I have been into and raising fish since childhood and have read and continue to read ANYTHING I can about them.