Common goldfish
Carassius auratus · family Cyprinidae
This page covers single-tailed common, comet and shubunkin goldfish. Fancy goldfish (fantails, orandas and similar) stay smaller: See fancy goldfish.
The common goldfish is a hardy, peaceful coldwater fish from Southern China that grows to 8–12 inches and can live 10–20 years. It needs a large, well-filtered tank of at least 75 gallons, cool water and plenty of regular water changes. The most important thing to know is that it produces a lot of waste, so it should never be kept in a bowl or small aquarium.
Edited by Marin Hale · last reviewed October 29, 2026 · How we check facts
What can live with a common goldfish?
Verdicts against every species in our database, from our compatibility rules. How verdicts work
| Verdict | Species | Why | Tank |
|---|---|---|---|
| Good match | Another common goldfish | No problems found: water, size, fins and temperament all check out. | 75 gal+ |
| Good match | Zebra nerite snail | No problems found: water, size, fins and temperament all check out. | 75 gal+ |
| Maybe | Fancy goldfish | Common goldfish are fast and outcompete slow fancy goldfish for food, and they grow much larger. Most keepers house them separately. | 75 gal+ |
| Avoid | Angelfish | Common goldfish need cool water; angelfish need tropical water. | — |
| Avoid | Betta fish | Common goldfish need cool water; betta fish need tropical water. | — |
| Avoid | Cherry shrimp | Common goldfish will hunt and eat cherry shrimp. | — |
| Avoid | Ember tetra | Common goldfish need cool water; ember tetras need tropical water. | — |
| Avoid | Guppy | Common goldfish need cool water; guppies need tropical water. | — |
| Avoid | Neon tetra | Common goldfish need cool water; neon tetras need tropical water. | — |
| Avoid | Pygmy corydoras | Common goldfish need cool water; pygmy corydoras need tropical water. | — |
| Avoid | Tiger barb | Common goldfish need cool water; tiger barbs need tropical water. | — |
Setup and care
| Heater | No heater. Common goldfish are coolwater fish (60–74°F); keep the tank out of direct sun. |
|---|---|
| Feeding | Rotate foods; feed what they eat in 2-3 minutes, once or twice a day |
| Substrate | Avoid jagged or crushed glass gravel; they forage in the substrate |
| Breeding | Breeds in captivity, especially in ponds; adults may eat young |
- Produces a lot of waste that quickly becomes toxic
- Rapid temperature changes can kill them, especially in small tanks
- Do not touch or pet; damages protective slime coat
- Temperatures over 30 °C (86 °F) can harm them
- Never keep in bowls, small aquariums or unfiltered containers
- Rapid changes in temperature or water chemistry can be fatal
Care tips
- Keep the water between 68 and 72 °F, which is the ideal range, and avoid sudden swings in temperature or water chemistry because they can be fatal.
- Use strong filtration and gentle aeration, and keep ammonia and nitrite at zero and nitrate under 20 mg/L with regular water changes.
- Choose smooth substrate and decorations, since goldfish forage in the gravel and sharp or abrasive items can tear fins; avoid jagged or crushed glass gravel and strong currents.
- Rotate their foods and feed only what they eat in 2–3 minutes, once or twice a day, to limit waste and avoid gulping air that can cause floating problems.
Questions
Do common goldfish need a heater?
Generally no, because they are a coldwater fish. They tolerate 60–74 °F, with 68–72 °F ideal, so the goal is a steady temperature in that range. Rapid temperature changes can kill them, especially in small tanks.
What do common goldfish eat?
They are omnivores, so offer a rotation of different foods. Feed what they will eat in 2–3 minutes, once or twice a day. Floating pellets and gulping air at the surface can cause buoyancy problems, including floating upside down.
What fish can live with common goldfish?
Other common goldfish and zebra nerite snails are fine. Most tropical fish, including angelfish, bettas, guppies, neon tetras and tiger barbs, are a poor match because they need warmer water, and small fish may be eaten. Cherry shrimp will be hunted and eaten. Fancy goldfish are a caution: common goldfish are faster, outcompete them for food and grow much larger, so most keepers house them separately.
How big do common goldfish get, and how many should I keep?
Adults reach 8–12 inches, and a smaller tank may stunt their growth. They should be kept in groups of at least 2, in a tank of at least 75 gallons. More fish means more waste, so you will need more filtration and more water changes.
Can common goldfish live in a bowl?
No. They need aeration and filtration, and their waste quickly becomes toxic in a bowl, small aquarium or unfiltered container. Also avoid a tank taller than 2 feet, which is likely too tall.
Sources
Each value is cross-checked across the references below. Where they disagreed, an editor chose a value and recorded why.
- Goldfish (en.wikipedia.org)
- Goldfish Care Guide (www.aqueon.com)
- How to Take Care of Goldfish (www.thesprucepets.com)
- Goldfish Tank Size? - Fact Based Goldfish Stocking Advice (lukesgoldies.com)
- GBIF taxonomy record
- Wikidata entry
Where each value comes from (13 facts)
| Fact | What each source says |
|---|---|
| Temperature editor decision | en.wikipedia.org: “The optimum temperature for goldfish is between 20 and 22 °C (68 and 72 °F).” aqueon.com: “The optimum temperature for fancy goldfish is 68° to 74° F, while comets and shubunkins should be kept between 60° and 70°F.” |
| Adult size editor decision | en.wikipedia.org: “Wild goldfish typically grow to between 4.7 inches (12 cm) and 8.7 inches (22 cm) but can reach 16 inches (41 cm).” |
| Smallest tank editor decision | en.wikipedia.org: “For common and comet varieties, each goldfish should have about 20 US gallons (76 L; 17 imp gal) of water.” aqueon.com: “adult common goldfish, comets and shubunkins should have at least 20 gallons of water per fish” thesprucepets.com: “You will need at least 20 gallons of water per goldfish” lukesgoldies.com: “If the goldfish is a small to medium-sized COMMON goldfish, the absolute minimum tank size is 35 gallons.” |
| Safe with plants | en.wikipedia.org: “Because goldfish eat live plants, thei” aqueon.com: “Larger goldfish will eat many types of live plants, with the possible exception of Cryptocorynes, Java fern and Anubias” |
| Water type | en.wikipedia.org: “The goldfish is classified as a coldwater fish, and can live in unheated aquaria at a temperature comfortable for humans.” aqueon.com: “Considered cold water fish, goldfish can also be kept in heated aquariums.” |
| Breeding type | en.wikipedia.org: “Goldfish, like all cyprinids, are egg-layers. Their eggs are adhesive and attach to aquatic vegetation” aqueon.com: “Goldfish are egg scatterers and are known to spawn in home aquariums.” |
| Native to | en.wikipedia.org: “Native to China, the goldfish is a relatively small member of the genus Carassius” aqueon.com: “native to Eastern Asia” |
| Breeding | en.wikipedia.org: “Most goldfish breed in captivity, particularly in pond settings.” aqueon.com: “To prevent eggs from being eaten by the adults or other fish in the aquarium, plants and other objects they are attached to can be moved” |
| pH editor decision | aqueon.com: “pH is not critical, but ideally should be between 7.0 and 8.4.” |
| Diet | aqueon.com: “Goldfish are omnivores, feeding largely on crustaceans, insects and plant matter in the wild.” |
| Substrate | aqueon.com: “Goldfish like to forage in the substrate, so avoid jagged or crushed glass gravel.” thesprucepets.com: “Goldfish are natural foragers and may spend most of their time digging around in the substrate of their aquarium or pond looking for food.” |
| Feeding | aqueon.com: “feed only what they can consume in 2 to 3 minutes, once or twice a day.” thesprucepets.com: “With water temperatures below 70F (21C), feed your goldfish at least once a day. Above this, you will need to feed your goldfish twice a day.” |
| Group size editor decision | lukesgoldies.com: “I always recommend getting at least 2 fish because fish are social and like having friends.” |
Editor decisions (8)
- Aqueon gives 60–74°F; Wikipedia's 68–72°F is the ideal.
- Wikipedia's 4.7–8.7 in describes wild fish; pet common and comet goldfish commonly reach 10–12 in.
- Sources' 20–35 gallons is only enough for juveniles. Adults are widely considered pond fish: 75+ gallons or a pond.
- Aqueon: ideally 7.0–8.4; goldfish do best in neutral to alkaline water.
- Luke's Goldies recommends at least two because goldfish are social.
- Peaceful, but fast and boisterous; they outcompete slower fish for food.
- Hardy, but their adult size and heavy waste make them hard to house properly.
- Long-lived; commonly 10–20 years with good care.