Goldfish
Carassius auratus
Also known as Common Goldfish, Fancy Goldfish
Edited by Ivan F. · Reviewed
Beginner verdict
Not the bowl fish many people expect. Goldfish keep growing, produce a lot of waste and need strong filtration, and a veterinarian writing for PetMD starts a juvenile at twenty gallons, adding space as it grows. Keep them in cooler water, apart from tropical tank mates.
Care at a glance
- Min tank size
- 20 US gal
- Footprint
- Not specified
- Temperature
- 65–75 °F
- pH
- 6.5–7.5
- Hardness
- 5–19 dGH
- Swim zone
- All Levels
- Min group
- Single fish
- Lifespan
- 10–15 years
Goldfish tank mates and swim zone
All Levels
Spends most of its time in this part of the tank.
Danio rerio
Tanichthys albonubes
Atya gabonensis
Large shrimp like Vampire Shrimp are usually safe from Goldfish, but may be nipped or harassed.
Atyopsis moluccensis
Large shrimp like Bamboo Shrimp are usually safe from Goldfish, but may be nipped or harassed.
Neritina natalensis
We found no direct source on goldfish with Nerite Snail, so treat this pairing with caution.
Pomacea diffusa
We found no direct source on goldfish with Mystery Snail, so treat this pairing with caution.
Paracheirodon innesi
Goldfish suit cooler water and are not suited to tropical tanks, so Neon Tetra is a poor match.
Paracheirodon axelrodi
Goldfish suit cooler water and are not suited to tropical tanks, so Cardinal Tetra is a poor match.
Hyphessobrycon amandae
Goldfish suit cooler water and are not suited to tropical tanks, so Ember Tetra is a poor match.
Hyphessobrycon herbertaxelrodi
Goldfish suit cooler water and are not suited to tropical tanks, so Black Neon Tetra is a poor match.
Hemigrammus erythrozonus
Goldfish suit cooler water and are not suited to tropical tanks, so Glowlight Tetra is a poor match.
Common tank-mate questions
Goldfish feeding and care
How to feed
- Feed a mix of flakes, pellets, frozen and freeze-dried foods made for goldfish.
- Choose sinking foods, which PetMD says help prevent bloating and buoyancy problems.
- Feed small portions you can see finished within a couple of minutes, because overfeeding fouls the water fast.
Telling males from females
Our sources do not describe a reliable way to tell the sexes apart, so we give none here.
Goldfish care mistakes to avoid
- Plan on one as the centerpiece of the tank, and read the tank-mate lists before adding others.
- Do not use a bowl or small tank. A juvenile needs at least our sourced minimum, and PetMD adds more space for each inch it grows.
- Do not keep them in a tropical tank. They suit cooler water.
- Use strong filtration, because they make more waste than similar-sized fish.
- Check your tank before you buy. Our sourced minimum is 20 US gallons.
Goldfish tank setup
A forgiving setup with room for a small community.
TankAt least 20 US gal (76 L)
The smallest tank our sources give for Goldfish. We list only tanks that hold this volume (allowing 10%, so a standard size counts).
Aqueon Standard Glass Aquarium 20 Long US
Aqueon Standard Glass Aquarium 29 Gallon US
Aqueon Standard Glass Aquarium 40 Breeder US
Eheim clearTank 73 Spain
Why we chose these (Best 20-Gallon Fish Tank: 20 Long or 29?). Nobody here has used or tested them.
Starter kitA kit with the tank, filter and light in one box
We list only kits whose tank fits Goldfish, up to twice its minimum volume. A kit whose heater has a fixed setting shows only when that setting is inside Goldfish's temperature range.
None of our picks for Spain suits this species. The options below are for the US, and we have not confirmed that they are sold in Spain.
Tetra Complete LED Aquarium Kit 20 Gallon US
Check the heater's setting
Tetra Complete LED Aquarium Kit 29 Gallon US
Check the heater's setting
Why we chose these (Best Aquarium Starter Kit: What to Look For). Nobody here has used or tested them.
FilterHang-on-back or large sponge filter
Easy to maintain and strong enough for a community without blasting the fish.
Seachem Tidal 55 Power Filter US
Marineland Penguin PRO 175 Power Filter US
Eheim LiBERTY 130 Hang-on Filter Spain
Seachem Tidal 35 Power Filter Spain
Why we chose these (Best Filter for a 20 to 29-Gallon Tank). Nobody here has used or tested them.
HeaterKeep it at 65–75 °F (18–24 °C)
Adjustable heater, about 5 W per gallon: 100 W at 20 gallons, about 150 W at 29. Enough power to hold a stable temperature in most homes. Size up for a cold room.
Aqueon Pro Adjustable Heater 100 W US
Aqueon Submersible Glass Heater 100 W US
Eheim Thermocontrol e 100 Heater Spain
Tetra HT 100 Electronic Heater Spain
Why we chose these (Best Heater for a 20 to 29-Gallon Tank). Nobody here has used or tested them.
Water conditionerDechlorinator such as Seachem Prime
Tap water contains chlorine or chloramine that harms fish.
Seachem Prime US
Fritz Complete Water Conditioner US
API Betta Water Conditioner US
sera aquatan Spain
Tetra AquaSafe Spain
Sold at Kiwoko · Sold at Tiendanimal · Sold at zooplus.es · Maker's details
Why we chose these (Best Water Conditioner for Betta Fish). Nobody here has used or tested them.
Test kitLiquid kit such as API Freshwater Master
Tracks ammonia, nitrite, nitrate and pH while the tank cycles.
API Freshwater Master Test Kit US
API General & Carbonate Hardness Test Kit US
See it at The Shrimp Farm (a retailer; affiliate link) · Sold at Bulk Reef Supply · Maker's details
sera aqua-test box (Cl) Spain
JBL PROAQUATEST COMBISET Plus NH4 Spain
Why we chose these (Best Test Kit for a Freshwater Aquarium). Nobody here has used or tested them.
SubstrateSand, gravel or pebbles all work, or no substrate at all, but avoid gravel small enough to swallow.
We are still choosing products for this.
Hiding places and decorGoldfish need plenty of hiding spots without crowding out open swimming space.
We are still choosing products for this.
PlantsEats or uproots plants
Cycle the tank before adding animals. See our guide on how to cycle a fish tank.
Where to buy Goldfish
We have not found a store that sells Goldfish under its scientific name yet. We add stores as we confirm them.
Live animals and plants travel by courier. Check the store's live-arrival guarantee, and only buy once your tank has cycled (see how to cycle a fish tank).
Some US states restrict certain species. Check our US state aquarium rules table and your state's own rules before you buy.
Check your local rules on Goldfish
Official lists name this animal or its close relatives. Rules differ by place, so check the rules where you live before you buy or keep one.
Minnesota
Minnesota lists goldfish as a regulated invasive species, which is a lighter category than prohibited. Never release a goldfish into a lake, river or pond.
Source: Minnesota Rules, part 6216.0260
New York
New York's invasive species rule lists goldfish as regulated, not prohibited. Never release a goldfish into a lake, river or pond.
Source: 6 NYCRR Part 575 prohibited and regulated animals (New York DEC)
Washington
Washington lists goldfish as a regulated type A species, not a prohibited one. Never release a goldfish into a lake, river or pond.
Never release aquarium animals or plants into the wild, including into ponds, rivers or drains.
This is general information, not legal advice. We last checked these lists on 4 November 2026, and the US state lists on 8 November 2026. Our US state aquarium rules table shows every state, including the ones whose lists we could not read. We did not check Spanish regional rules, and other countries have their own.
Goldfish FAQ
What size tank do Goldfish need?
Our sourced minimum is 20 US gallons (76 liters). A bigger tank is always easier to keep stable.
How many Goldfish should I keep?
One is fine in a tank this size. Add more only with plenty of extra room and cover.
What can live with Goldfish?
Good matches on our list include Zebra Danio and White Cloud Mountain Minnow. Avoid Neon Tetra and Cardinal Tetra.
How long do Goldfish live?
Care guides report about 10–15 years. Stable water and a good diet make the biggest difference.
How big do goldfish get?
PetMD says most goldfish are about one to fourteen inches long, and some can grow up to eighteen. They do not grow to fit their tank, so plan for an adult.
Goldfish facts and sources
- Family
- Cyprinidae
- Native to
- East Asia, including China and Japan
- Adult size
- 3.9 in (10 cm)
- Temperament
- Peaceful
- Social needs
- Solitary/Centerpiece
- Diet
- Omnivore
- Water flow
- Gentle
- Substrate
- Smooth Gravel
- Live plants
- Warning - Eats/Uproots Plants
- Shrimp
- Will Eat Shrimp
- Fin nipping
- None
- Vulnerable to nippers
- Yes
- Breeding
- Difficult in Home Tanks
Spotted something wrong? Report a parameter correction. For a sick fish, see our veterinary disclaimer.