Identify the variety before choosing its home. Fancy goldfish and slim-bodied common, comet or shubunkin goldfish have different adult space and swimming needs. A bowl is not an appropriate long-term home.

Size and companions

SPCA New Zealand starts its fancy-goldfish guidance at 75 litres, plus 40 litres for each additional fish. RSPCA UK states at least 60 litres per goldfish. These are different recommendations, not interchangeable stocking guarantees. Check usable dimensions against adult size and provide more space as necessary.

Common and comet types need much more room as they grow; plan a suitable pond or a specialist-assessed large aquarium. Goldfish benefit from compatible goldfish company, but do not mix fast, strong swimmers with fancies that struggle to compete for food.

Water and equipment

Fit efficient filtration and provide adequate aeration. Fancy varieties may struggle in a powerful current, so adjust the flow. Use a thermometer and maintain stable, variety-appropriate conditions; avoid direct sun and sudden changes. Establish biological filtration before adding fish. Test for ammonia, nitrite, nitrate and pH; aim for zero ammonia and nitrite. Use conditioner on replacement tap water and maintain the filter's beneficial bacteria.

Feeding and enrichment

Offer an appropriate goldfish diet in measured small portions. Sinking food can suit fancy fish. Remove leftovers, check that slower fish eat, and avoid treating feeding as an unlimited activity. Supply safe plant cover and smooth furnishings while retaining open swimming room.

Daily checks

Observe appetite, fins, balance, breathing and activity. For new buoyancy trouble, wounds or persistent abnormal behaviour, test the water and contact a fish-experienced vet rather than assuming a single diagnosis. Never release unwanted fish into natural waterways; arrange responsible rehoming.

Sources checked

Guide copy checked on 2026-11-08. This is a source-based editorial review, not independent veterinary review.