I've never heard that but I'm no expert on Gold Fish. Would they produce more wast than say 40 1.5" African Cichlid fry feed three times a day? I've done that using a 20 gallon tank as a qt tank with the above linked filter for a month with no problems.
Or if you want a small canister, you could try Tom's Rapid minI canister filter. They usually get decent reviews online. The only negative that you may see is that it is made cheap, mainly the tubing. This can be remedied if you really want to. They have numerous videos of it online. I would not put this on anything bigger than a 20G though as the flow rate is not super impressive. Just another option. It also hangs from your tank like a HOB btw.