Surprising to hear answers that imply goldfish don't need much space. I have been keeping goldfish for almost 12 years and I believe the ideal living space for them is 10 GALLONS per fish for optimal growth and health, even more if you want some great looking fish. With the proper space, filtration, frequent water changes, and diet, goldfish can get huge and colorful. I have orandas that are over 10 years old and bigger than softballs in body mass. I have 1 bluescale pompom that is 8 years old and bigger than the other 3. These guys are kept in my 75 gallon showtank in the living room with a couple of cory catfish and a few big gold and black snails. Because of the size of the tank, number of fish, filtration, and diet, I only change my water every 2 weeks and it's been algae free for many years with NO ugly PLECO's!