Get a Huge Tank

All fish

Goldfish

Carassius auratus

Freshwater Captive bred worldwide Usually captive bred

A cold-water carp that produces heavy waste and grows far bigger than the bowl it is sold in. Plain-bodied types reach 25 cm or more. Filtration should be rated well above the tank volume, and no heater is needed.

Also called: Carp, Crucian carp, Edible goldfish, Gibel carp.

25 cm adult length, drawn to scale. deep body.

Outgrows a typical home tank. Check this fish against the adult size above before buying a juvenile. The minimum shown is the least it is kept in for good, not a comfortable size.

Try it in the planner Opens a tank sized to its minimum with 2 fish added.

What it needs

ItemValueBecause
Adult length 25 cm Used for the Space check: the tank must be long enough for the fish to turn round.
Smallest tank 200 L, at least 120 cm long estimated The least water and floor length this species is kept in for good, as a single fish or smallest group.
Extra water per added fish 50 L estimated What each further fish adds once the minimum is met.
Waste load Class 5 of 5 estimated How much waste an adult makes against its size. Feeds the Load check.
Temperature 10 to 22 C Stock sharing a tank need overlapping ranges.
pH 6.8 to 8 Compared with tankmates in the Water check.
Hardness GH 8 to 20, KH 4 to 12 Degrees of general and carbonate hardness.
Flow Medium Low-flow fish are stressed in a strong current.
Light Moderate Matched to the lighting class on the needs sheet.
Group size At least 2, ideally 3 Kept alone or in small numbers it hides, fades or turns on tankmates.
Temperament Peaceful Not territorial.
Swims in All levels Fish that use different levels share a tank more easily.
Lifespan About 15 years A fish is a long commitment.
Experience Suits a first tank A guide to how forgiving the species is of mistakes.

Tags marked estimated are judged from the size and habits of the species rather than measured, so treat them as a sensible default.

Diet and tank layout

Goldfish is an herbivore that swims in all levels of the tank. It eats or uproots plants, so choose hard-leaved species or none. It digs, so anchor plants and keep hard rock off loose sand. It will eat fish small enough to swallow.

Tankmates

Works with

No close matches in the data. Check the pair tool.

Depends

Avoid

Compare any two fish on the compatibility page, or print the equipment for a stock on the needs sheet. How this is worked out: the method.