How should I give maintenance to a 125 gallon goldfish tank?

First of all I have to ask… why would you want goldfish if you have 125 gal tank? Goldfish are considered the dirtiest fish. They will create a mess in there own. A community tank containing a large variety of species can be very interesting. I had a 125gallon tank. read more

you can use a slightly smaller tank (20 gallons for one fish, then 10 gallons for each additional fish). You’ll probably be OK with two small fancies in a 20 gallon, but you’ll have to do water changes more frequently, and they will not grow as large as they would in a larger tank. read more

This lead to me getting answers anywhere from 125 gallons for a single fish to 600 gallons. I'm sure no one in their common sense would only add a single 8" fish to a 125 gallon aquarium. The only information I could find online says somewhere between 30 to 40 gallons per fish, or 10 to 20 gallons for each additional fish. read more

A 10 gallon tank is enough for a fancy goldfish (meaning the kind that have double-tails) but not enough for a slim-bodied goldfish (like the common). This is because they start out small but they can get to be over a foot in length. 40 gallons is the recommended minimum for them. read more