Aquariumgoldfish · freshwater
Common / Comet Goldfish: adult size, tank size & tankmates
The Common / Comet Goldfish (Carassius auratus) grows to about 19 in (48 cm TL). It needs a tank at least 39 inches long and about 42 gallons. Keep at least 5 together, at 68–75°F.
How big it really gets
Drawn to scale against common tank lengths. Green bars meet the minimum tank length from our sources.
Outgrows most home tanks. Sold for cents as bowl pets; reaches 12-16 inches with heavy ammonia output that rapidly kills fish in small uncycled tanks.
Will it fit your tank?
Quick facts
- Adult size
- 19 in (48 cm TL)
- Minimum tank
- 39 inches long and about 42 gallons
- Temperature
- 68–75°F
- pH
- 6–8
- Hardness
- 5–19 dGH
- Group size
- 5+
- With other fish
- peaceful
- With its own kind
- peaceful
- Swims
- all levels
- Diet
- omnivore
- Care level
- intermediate
- Lifespan
- 30 years
Watch for: eats small fish · eats shrimp · eats snails · eats live plants · jumps, so keep a lid
Common / Comet Goldfish tankmates
Checked with the same rules as our tank builder: temperature overlap, pH and hardness, predation and mouth size, fin-nipping and temperament. Tank size is left out here; check it in the builder.
Good tankmates
- Harlequin RasboraAdult ~2.1 in · 70–82°F
- Cherry BarbAdult ~2.4 in · 68–81°F
- Rummy-nose TetraAdult ~2.4 in · 73–79°F
- GuppyAdult ~2.8 in · 63–82°F
- PlatyAdult ~2.4 in · 68–79°F
- Honey GouramiAdult ~2.6 in · 72–81°F
- Dwarf GouramiNeeds careAdult ~4.2 in · 72–81°F
- BettaNeeds careAdult ~3.3 in · 72–86°F
- Bronze CoryAdult ~3.5 in · 70–81°F
- Panda CoryAdult ~2.4 in · 72–77°F
Use caution
- Pearl GouramiCommon / Comet Goldfish and Pearl Gourami only share 75–75°F. That's a tight window.
- Bolivian RamCommon / Comet Goldfish and Bolivian Ram only share 75–75°F. That's a tight window.
- KribensisCommon / Comet Goldfish and Kribensis only share 75–75°F. That's a tight window.
- AngelfishNeeds careCommon / Comet Goldfish and Angelfish only share 75–75°F. That's a tight window.
- Sterbai CoryCommon / Comet Goldfish and Sterbai Cory only share 75–75°F. That's a tight window.
- Clown LoachOutgrows tanksCommon / Comet Goldfish and Clown Loach only share 75–75°F. That's a tight window.
- Diamond TetraCommon / Comet Goldfish and Diamond Tetra only share 75–75°F. That's a tight window.
- Electric Yellow LabNeeds careCommon / Comet Goldfish and Electric Yellow Lab only share 75–75°F. That's a tight window.
Avoid
- Neon TetraCommon / Comet Goldfish eats small fish, and Neon Tetra only grows to about 1.4 in.
- Cardinal TetraCommon / Comet Goldfish eats small fish, and Cardinal Tetra only grows to about 1.7 in.
- Ember TetraCommon / Comet Goldfish eats small fish, and Ember Tetra only grows to about 0.9 in.
- Chili RasboraCommon / Comet Goldfish eats small fish, and Chili Rasbora only grows to about 0.9 in.
- Celestial Pearl DanioCommon / Comet Goldfish eats small fish, and Celestial Pearl Danio only grows to about 1 in.
- Black Neon TetraCommon / Comet Goldfish eats small fish, and Black Neon Tetra only grows to about 1.7 in.
- Glowlight TetraCommon / Comet Goldfish and Glowlight Tetra only share 75–75°F. That's a tight window.
- Lemon TetraCommon / Comet Goldfish eats small fish, and Lemon Tetra only grows to about 1.9 in.
All 105 species we checked against the Common / Comet Goldfish
| Species | Verdict | Why |
|---|---|---|
| Bala Shark | Compatible | No conflicts found |
| Betta | Compatible | No conflicts found |
| Black Skirt Tetra | Compatible | No conflicts found |
| Bleeding Heart Tetra | Compatible | No conflicts found |
| Bristlenose Pleco | Compatible | No conflicts found |
| Bronze Cory | Compatible | No conflicts found |
| Buenos Aires Tetra | Compatible | No conflicts found |
| Cherry Barb | Compatible | No conflicts found |
| Clown Pleco | Compatible | No conflicts found |
| Cockatoo Dwarf Cichlid | Compatible | No conflicts found |
| Common Pleco | Compatible | No conflicts found |
| Congo Tetra | Compatible | No conflicts found |
| Denison Barb | Compatible | No conflicts found |
| Dwarf Gourami | Compatible | No conflicts found |
| Dwarf Neon Rainbowfish | Compatible | No conflicts found |
| Electric Blue Acara | Compatible | No conflicts found |
| Fancy Goldfish | Compatible | No conflicts found |
| Firemouth Cichlid | Compatible | No conflicts found |
| Giant Danio | Compatible | No conflicts found |
| Glass Catfish | Compatible | No conflicts found |
| Gold Barb | Compatible | No conflicts found |
| Guppy | Compatible | No conflicts found |
| Harlequin Rasbora | Compatible | No conflicts found |
| Hillstream Loach | Compatible | No conflicts found |
| Honey Gourami | Compatible | No conflicts found |
| Iridescent Shark | Compatible | No conflicts found |
| Julii Cory | Compatible | No conflicts found |
| Kissing Gourami | Compatible | No conflicts found |
| Kuhli Loach | Compatible | No conflicts found |
| Molly | Compatible | No conflicts found |
| Odessa Barb | Compatible | No conflicts found |
| Oscar | Compatible | No conflicts found |
| Panda Cory | Compatible | No conflicts found |
| Paradise Fish | Compatible | No conflicts found |
| Pearl Danio | Compatible | No conflicts found |
| Peppered Cory | Compatible | No conflicts found |
| Pictus Catfish | Compatible | No conflicts found |
| Platy | Compatible | No conflicts found |
| Pristella Tetra | Compatible | No conflicts found |
| Rainbow Shark | Compatible | No conflicts found |
| Red-Tail Shark | Compatible | No conflicts found |
| Rosy Barb | Compatible | No conflicts found |
| Rummy-nose Tetra | Compatible | No conflicts found |
| Scissortail Rasbora | Compatible | No conflicts found |
| Siamese Algae Eater | Compatible | No conflicts found |
| Silver Tip Tetra | Compatible | No conflicts found |
| Swordtail | Compatible | No conflicts found |
| Tiger Barb | Compatible | No conflicts found |
| Tinfoil Barb | Compatible | No conflicts found |
| Variatus Platy | Compatible | No conflicts found |
| Weather Loach | Compatible | No conflicts found |
| Yoyo Loach | Compatible | No conflicts found |
| Zebra Danio | Compatible | No conflicts found |
| Angelfish | Caution | Common / Comet Goldfish and Angelfish only share 75–75°F. That's a tight window. |
| Bolivian Ram | Caution | Common / Comet Goldfish and Bolivian Ram only share 75–75°F. That's a tight window. |
| Clown Loach | Caution | Common / Comet Goldfish and Clown Loach only share 75–75°F. That's a tight window. |
| Diamond Tetra | Caution | Common / Comet Goldfish and Diamond Tetra only share 75–75°F. That's a tight window. |
| Electric Yellow Lab | Caution | Common / Comet Goldfish and Electric Yellow Lab only share 75–75°F. That's a tight window. |
| Forktail Blue-eye | Caution | Common / Comet Goldfish and Forktail Blue-eye only share 75–75°F. That's a tight window. |
| Head-and-tail-light Tetra | Caution | Common / Comet Goldfish and Head-and-tail-light Tetra only share 75–75°F. That's a tight window. |
| Kribensis | Caution | Common / Comet Goldfish and Kribensis only share 75–75°F. That's a tight window. |
| Pearl Gourami | Caution | Common / Comet Goldfish and Pearl Gourami only share 75–75°F. That's a tight window. |
| Sterbai Cory | Caution | Common / Comet Goldfish and Sterbai Cory only share 75–75°F. That's a tight window. |
| Three-spot Gourami | Caution | Common / Comet Goldfish and Three-spot Gourami only share 75–75°F. That's a tight window. |
| Upside-down Catfish | Caution | Common / Comet Goldfish and Upside-down Catfish only share 75–75°F. That's a tight window. |
| African Dwarf Frog | Avoid | Common / Comet Goldfish and African Dwarf Frog only share 74–75°F. That's a tight window.; Common / Comet Goldfish eats small fish, and African Dwarf Frog only grows to about 1.4 in. |
| Amano Shrimp | Avoid | Common / Comet Goldfish will eat Amano Shrimp. |
| Assassin Snail | Avoid | Common / Comet Goldfish and Assassin Snail only share 75–75°F. That's a tight window.; Common / Comet Goldfish eats snails, including Assassin Snail. |
| Bamboo Shrimp | Avoid | Common / Comet Goldfish will eat Bamboo Shrimp. |
| Black Neon Tetra | Avoid | Common / Comet Goldfish eats small fish, and Black Neon Tetra only grows to about 1.7 in. |
| Blood Parrot Cichlid | Avoid | Common / Comet Goldfish (68–75°F) and Blood Parrot Cichlid (76–80°F) need different temperatures. |
| Boesemani Rainbowfish | Avoid | Common / Comet Goldfish (68–75°F) and Boesemani Rainbowfish (81–86°F) need different temperatures. |
| Bumblebee Goby | Avoid | Common / Comet Goldfish eats small fish, and Bumblebee Goby only grows to about 1.7 in. |
| Cardinal Tetra | Avoid | Common / Comet Goldfish eats small fish, and Cardinal Tetra only grows to about 1.7 in. |
| Celestial Pearl Danio | Avoid | Common / Comet Goldfish eats small fish, and Celestial Pearl Danio only grows to about 1 in. |
| Cherry Shrimp | Avoid | Common / Comet Goldfish will eat Cherry Shrimp. |
| Chili Rasbora | Avoid | Common / Comet Goldfish eats small fish, and Chili Rasbora only grows to about 0.9 in. |
| Chinese Algae Eater | Avoid | Chinese Algae Eater is aggressive toward tankmates. Common / Comet Goldfish is peaceful. |
| Clown Killifish | Avoid | Common / Comet Goldfish eats small fish, and Clown Killifish only grows to about 1.6 in. |
| Convict Cichlid | Avoid | Common / Comet Goldfish and Convict Cichlid only share 75–75°F. That's a tight window.; Convict Cichlid is aggressive toward tankmates. Common / Comet Goldfish is peaceful. |
| Crystal Red Shrimp | Avoid | Common / Comet Goldfish will eat Crystal Red Shrimp. |
| Discus | Avoid | Common / Comet Goldfish (68–75°F) and Discus (79–86°F) need different temperatures. |
| Ember Tetra | Avoid | Common / Comet Goldfish eats small fish, and Ember Tetra only grows to about 0.9 in. |
| Endler's Livebearer | Avoid | Common / Comet Goldfish and Endler's Livebearer only share 75–75°F. That's a tight window.; Common / Comet Goldfish eats small fish, and Endler's Livebearer only grows to about 1.2 in. |
| German Blue Ram | Avoid | Common / Comet Goldfish (68–75°F) and German Blue Ram (81–86°F) need different temperatures.; Common / Comet Goldfish eats small fish, and German Blue Ram only grows to about 1.9 in. |
| Ghost Shrimp | Avoid | Common / Comet Goldfish will eat Ghost Shrimp. |
| Glowlight Tetra | Avoid | Common / Comet Goldfish and Glowlight Tetra only share 75–75°F. That's a tight window.; Common / Comet Goldfish eats small fish, and Glowlight Tetra only grows to about 1.9 in. |
| Japanese Trapdoor Snail | Avoid | Common / Comet Goldfish eats snails, including Japanese Trapdoor Snail. |
| Lambchop Rasbora | Avoid | Common / Comet Goldfish eats small fish, and Lambchop Rasbora only grows to about 1.4 in. |
| Lemon Tetra | Avoid | Common / Comet Goldfish eats small fish, and Lemon Tetra only grows to about 1.9 in. |
| Malaysian Trumpet Snail | Avoid | Common / Comet Goldfish eats snails, including Malaysian Trumpet Snail. |
| Marbled Hatchetfish | Avoid | Common / Comet Goldfish eats small fish, and Marbled Hatchetfish only grows to about 1.7 in. |
| Moonlight Gourami | Avoid | Common / Comet Goldfish (68–75°F) and Moonlight Gourami (77–86°F) need different temperatures. |
| Mystery Snail | Avoid | Common / Comet Goldfish eats snails, including Mystery Snail.; Common / Comet Goldfish (pH 6–8) and Mystery Snail (pH unknown) prefer different pH. |
| Neon Tetra | Avoid | Common / Comet Goldfish eats small fish, and Neon Tetra only grows to about 1.4 in. |
| Nerite Snail | Avoid | Common / Comet Goldfish eats snails, including Nerite Snail. |
| Otocinclus | Avoid | Common / Comet Goldfish eats small fish, and Otocinclus only grows to about 1.7 in. |
| Pea Puffer | Avoid | Common / Comet Goldfish eats small fish, and Pea Puffer only grows to about 1.4 in. |
| Penguin Tetra | Avoid | Common / Comet Goldfish eats small fish, and Penguin Tetra only grows to about 1.7 in. |
| Pygmy Cory | Avoid | Common / Comet Goldfish eats small fish, and Pygmy Cory only grows to about 1.4 in. |
| Ramshorn Snail | Avoid | Common / Comet Goldfish eats snails, including Ramshorn Snail. |
| Serpae Tetra | Avoid | Common / Comet Goldfish eats small fish, and Serpae Tetra only grows to about 1.9 in. |
| Silver Hatchetfish | Avoid | Common / Comet Goldfish eats small fish, and Silver Hatchetfish only grows to about 1.9 in. |
| Sparkling Gourami | Avoid | Common / Comet Goldfish eats small fish, and Sparkling Gourami only grows to about 1.9 in. |
| White Cloud Mountain Minnow | Avoid | Common / Comet Goldfish eats small fish, and White Cloud Mountain Minnow only grows to about 1.9 in. |
Care notes
Needs: Lacks a stomach resulting in constant ammonia discharge; coldwater species incompatible with tropical heat; ideal for ponds
Group: Social cyprinid; best kept in pairs or groups with other fast single-tailed goldfish in large systems
Temperament: peaceful toward other fish, peaceful toward its own kind. Lives in the whole tank.
Common questions
How big does a Common / Comet Goldfish get?
About 19 inches (48 cm TL) as an adult, according to fishbase.se.
What size tank does a Common / Comet Goldfish need?
At least 39 inches long and about 42 gallons. The smallest standard tank that meets that is a 55 gallon.
How many Common / Comet Goldfishs should be kept together?
At least 5. Social cyprinid; best kept in pairs or groups with other fast single-tailed goldfish in large systems
What fish can live with a Common / Comet Goldfish?
Species that passed every check include Harlequin Rasbora, Cherry Barb, Rummy-nose Tetra, Guppy, Platy, Honey Gourami.
Gear for a Common / Comet Goldfish setup
TankSmallest standard tank that meets its minimum: 55 gallon (48 in long).Find on Amazon →ThermometerCool-water fish: skip the heater, watch summer highs.Find on Amazon →LidIt jumps. A full lid keeps it in the tank.Find on Amazon →FoodA quality flake or micro-pellet as a staple.Find on Amazon →Test kitCheck ammonia, nitrite and pH. Cycle the tank before adding fish.Find on Amazon →
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Related guides
Sources
Values come from these pages, in our own words. Status: verified. Last reviewed 2026-10-12.
- fishbase.se /summary/Carassius-auratus.html
- nas.er.usgs.gov /queries/factsheet.aspx?SpeciesID=508