For more on setting up an appropriate habitat, see our goldfish aquarium setup guide. 2. Goldfish Need More Oxygen Than Other Fish.Step-by-step guide to setting up the perfect goldfish tank. Feeding Goldfish: Complete Diet Guide.
Goldfish Tank Setup. Why Goldfish Should Not Be Kept in Bowls.Its highly recommended that you choose an external filter which hangs beside your goldfish tank. Although a bit on the pricier side, it works 10x better than the internal one, and wont take up your tank space at all.
TLDR Best Pick For Goldfish Tank Filter. If your aquarium is 100 gallons and up, then the Fluval FX6 High Performance Aquarium Canister Filter is your best option.

C4 filter for tanks up to 70 gallons. The Fluval C4 filter features a comprehensive 5-stage filtration system that effectively removes debris and toxins. Its innovative biological chamber accelerates beneficial nitrification, suitable for both fresh and saltwater setups.
Tetra Whisper Power Filter. Setting up a goldfish tank with a filter does not need to be cumbersome. If you pick the right filter, you can rest assured that your goldfish won't be harmed.

Setting up a bioreactor is not as easy as it sometimes sounds. Which sensors do I have to calibrate before autoclaving? Is it important to protect the filters with foil from water condensate in the autoclave?