No Filter?

[Gurglar]

Could a goldfish live without a filter if there was an airstone in the tank and I was doing 20% water changes every 2 days?

 

[black angel]

To do that successfully you would need to test the ammonia every day and then change the water accordingly. Depending on size of tank this could be from twice a day to once or twice a week.

 

[n3ont3tra]

It's so much better and easier if you get a filter, they really aren't too expensive.