Goldfish
Carassius auratus
The coldwater classic with hundreds of breeds; lives 10–15 years or more, makes lots of waste and needs a roomy, well-filtered tank.
Key facts
- Body length
- 5.9 in without fins
- Minimum tank
- 24 gallons
- Group
- 2+
- Temperament
- Peaceful
- Care level
- 3 / 5
- Lifespan
- 10–15 years
- Diet
- Goldfish pellets, gel food, blanched peas and vegetables
- Origin
- Domesticated; wild ancestor from China
- Hardier than75%
- Bigger than73%
- Calmer than68%
Water: their range vs yours
Goldfish tank mates
- Peppered coryGets along in shared water.Good mates
- Rosy barbGets along in shared water.Good mates
- Bladder snailGets along in shared water.Good mates
- Ramshorn snailGets along in shared water.Good mates
- Denison barbGets along in shared water.Good mates
- Giant danioGets along in shared water.Good mates
- Gold barbGets along in shared water.Good mates
- Great pond snailGets along in shared water.Good mates
- Butterfly hillstream loachGets along in shared water.Good mates
- BettaGoldfish needs cool water; bettas need tropical heat.Risky
- AngelfishGoldfish needs cool water; angelfish need tropical heat.Risky
- Black widow tetraGoldfish can eat young or small Black widow tetra; adults are big enough to be safe.Risky
- Blood parrot cichlidGoldfish outcompetes the slow-eating Blood parrot cichlid for food; target-feed to make sure it eats.Risky
- Blue dolphin cichlidBlue dolphin cichlid can eat young or small Goldfish; adults are big enough to be safe.Risky
- Bristlenose plecoGoldfish needs cool water; bristlenose plecos need tropical heat.Risky
- Neon tetraGoldfish can eat Neon tetra: prey body depth 0.7 cm ≤ mouth 3.0 cm.Avoid
- Harlequin rasboraGoldfish can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 3.0 cm.Avoid
- Fancy guppyGoldfish can eat Fancy guppy: prey body depth 0.8 cm ≤ mouth 3.0 cm.Avoid
- Panda corydorasGoldfish can eat Panda corydoras: prey body depth 2.4 cm ≤ mouth 3.0 cm.Avoid
- OtocinclusGoldfish can eat Otocinclus: prey body depth 0.7 cm ≤ mouth 3.0 cm.Avoid
- Cherry shrimpGoldfish can eat Cherry shrimp: prey body depth 0.8 cm ≤ mouth 3.0 cm.Avoid
How we check
The numbers the tank model uses for goldfish: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 15 cm (TL)
- Adult mass
- 43.18 g
- Bioload at 25 °C
- 14.36 BU
- Min. water
- 76 L net
- Min. footprint
- 60 × 30 cm per specimen
- Group
- 2+ (best 2)
- Swims in
- middle, bottom
- Flow
- low
- Body / fins
- round, long trailing fins
- Diet type
- omnivore plant
- Fin nipper
- none
- Sensitive to
- —
Sources: FishBase: Carassius auratus · Aquarium Co-Op: Fancy Goldfish Care Guide · RSPCA Australia: How should I care for my goldfish? · PetMD: How To Take Care of Goldfish
Care notes
Goldfish are domesticated forms of a carp from still and slow waters of China, from sleek comets to round fancy breeds like orandas and ranchus. They need no heater and do best at 50–75°F.
Start with about 20 gallons for the first fish and add roughly 10 gallons for each one after, with a strong filter. Keep at least two, avoid tropical fish and fin nippers like tiger barbs, and expect soft plants to be eaten or dug up.
Questions
What size tank does a goldfish need?
At least 24 gallons (76 litres of water after decor). Adults reach about 5.9 inches without fins.
How many goldfish should be kept together?
Keep at least 2, ideally 2 or more: fewer feel exposed and hide or turn nippy.
What water do goldfish need?
50–75 °F, pH 6.5–8 and 5–19 dGH. Goldfish come from Domesticated; wild ancestor from China.
How long do goldfish live?
10–15 years with good care.
What fish can live with goldfish?
Good tank mates include Peppered cory, Rosy barb, Bladder snail, Ramshorn snail and Denison barb. Each is checked both ways for size, fin nipping, temperament, territory and shared water.