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Reckon what your pet actually needs.

Common / Comet Goldfish Stocking

Minimum 55 gal · 12" adult · high bioload · peaceful.

Fish (enter how many of each)
Neon Tetra 1.5" · low bioload · min 10 gal
Guppy 2" · low bioload · min 10 gal
Southern Platy 2.5" · low bioload · min 10 gal
Betta (Siamese Fighting Fish) 2.5" · low bioload · min 5 gal
Fancy Goldfish 8" · high bioload · min 30 gal
Common / Comet Goldfish 12" · high bioload · min 55 gal
Zebra Danio 2" · low bioload · min 10 gal
Harlequin Rasbora 2" · low bioload · min 10 gal
Glowlight Tetra 1.5" · low bioload · min 10 gal
Ember Tetra 0.8" · low bioload · min 10 gal
Angelfish 6" · medium bioload · min 30 gal
Molly 4" · medium bioload · min 20 gal
Chinese Algae Eater 10" · medium bioload · min 50 gal
Discus 6" · medium bioload · min 55 gal
Oscar 14" · high bioload · min 75 gal
Common Pleco (Suckermouth Catfish) 24" · high bioload · min 125 gal
Tiger Barb 3" · medium bioload · min 20 gal
Cherry Barb 2" · low bioload · min 15 gal
Corydoras Catfish 2.5" · low bioload · min 20 gal
Swordtail 4" · low bioload · min 20 gal
Flowerhorn Cichlid 15" · high bioload · min 75 gal

Estimated bioload

51%

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    Bioload-based: it weighs adult size and waste output, not the oversimplified "1 inch per gallon" rule.

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    Keeping Common / Comet Goldfish

    The Common / Comet Goldfish grows to about 12 inches and needs a minimum of 55 gallons. Its bioload is high, meaning it produces a large amount of waste for its size, a key factor the "one inch per gallon" rule ignores. It doesn't need a large group, but plan tankmates around its temperament. Temperament is peaceful, making it a good community fish. Use the calculator above to see how a group fits your tank's real volume before you buy.

    Before you add this species

    Tanks that clear the 55-gallon minimum

    Real inside dimensions and filled weight for the standard sizes that can house a Common / Comet Goldfish.

    Species to plan alongside the Common / Comet Goldfish

    Closest on temperament and tank-size requirement. Run the whole list through the calculator before you buy: bioload adds up across species, not per species.

    • Discus55 gal min · 6" adult · medium bioload · peaceful
    • Fancy Goldfish30 gal min · 8" adult · high bioload · peaceful
    • Molly20 gal min · 4" adult · medium bioload · peaceful
    • Corydoras Catfish20 gal min · 2.5" adult · low bioload · peaceful
    • Swordtail20 gal min · 4" adult · low bioload · peaceful
    • Cherry Barb15 gal min · 2" adult · low bioload · peaceful

    Frequently asked questions

    What size tank does a Common / Comet Goldfish need?

    At least 55 gallons. They can be kept without a large group, but check tankmate compatibility.

    Is the Common / Comet Goldfish peaceful?

    Temperament is peaceful. Reaching about 12" as an adult with a high bioload, plan tankmates and filtration accordingly.

    Keep going with the same pet

    Not sure of your tank's exact gallons? Measure it with the aquarium volume calculator first.

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