At a glance the quick version
Looks how to spot one
Scaled, dorsal-less twin-tailed goldfish with fluid-filled eye sacs
A small, smoothly curved goldfish with no dorsal fin and a double tail. Its upturned eyes each sit above a large, soft bubble of fluid that wobbles gently as it swims. The bubbles start forming about three months after hatching; some recent strains even carry four sacs.13
Personality what they are like
Very gentle and calm. A slow swimmer with a bobbing head, it does best away from boisterous fish, alongside other bubble eyes, celestials, telescopes and Black Moors.1
Daily activity how busy a day looks
Low. Prefers calm water with soft flow and plenty of unobstructed space.14
Grooming and care the hands-on bits
Needs a good filter, regular partial water changes with dechlorinated, temperature-matched water, and routine tests showing zero ammonia and nitrite. Choose smooth decor with no sharp edges, and fit a gentle filter with a covered intake to suit its soft eye sacs.45
Home where they are happiest
Keep in a filtered aquarium, not a bowl. Aqueon suggests at least 40 litres (10 US gallons) per adult fancy goldfish, while the RSPCA advises at least 60 litres per goldfish, with wider tanks giving more stable water. Fancy goldfish are comfortable at about 20-23 °C (Aqueon gives 68-74 °F), and the RSPCA notes goldfish in general live at 10-21 °C without a heater. A pH of roughly 6.0-8.4 is fine (FishBase gives 6.0-8.0, Aqueon 7.0-8.4).546
Food basics what goes in the bowl
Omnivore. Offer a goldfish flake, granule or sinking pellet once or twice a day, only as much as is eaten in two to three minutes, with frozen or live foods as occasional treats. Give it time to find food, as it is a slow, careful feeder.56
Company who they like around
Sociable; FishBase suggests goldfish in groups of five or more. Ideally kept in its own tank with other bubble eyes or similar slow fancies.61
The story where it all began
The bubble eye was developed in China from the toadhead, or hama-tou, a goldfish with upturned eyes and small bladder-like sacs. Breeders selected for ever larger sacs, and the toadhead is thought to be the ancestor of the celestial too.12
Fun facts for the dinner table
Recognised by the official bits
- Taxonomy
- Small, dorsal-less twin-tailed fancy goldfish with a large fluid-filled sac under each eye3
- IUCN Red List
- The parent species Carassius auratus is assessed as Least Concern6
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Bubble Eye Goldfish. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- Feedingevery day
- Water changeAbout 25 to 30% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseevery month
Owner questions the things everyone asks
How often should I feed my Bubble Eye Goldfish?
Feed once or twice a day, only as much as your fish can eat in two to three minutes. Furry Diary's starting plan suggests feeding once daily. Give it time to find food as it is a slow, careful feeder.56 Furry Diary plan
What does a Bubble Eye Goldfish eat, and what should it never eat?
It is an omnivore; offer goldfish flake, granule or sinking pellet, with frozen or live foods as occasional treats. The facts do not specify foods to avoid, so ask your vet for a complete list of unsafe items.56
How much space does a Bubble Eye Goldfish need?
A filtered aquarium is essential, not a bowl. Aim for at least 40 to 60 litres per adult fancy goldfish, with a wider tank for more stable water conditions.54
What temperature, light or water does a Bubble Eye Goldfish need?
Keep water temperature around 20-23°C (68-74°F) for fancy goldfish, though they can tolerate cooler ranges. Maintain pH between 6.0 and 8.4. Use dechlorinated water and ensure zero ammonia and nitrite.546
How often should I clean a Bubble Eye Goldfish's home?
Perform a 25-30% water change weekly, test water weekly, clean glass weekly, and rinse the filter monthly. Always use dechlorinated, temperature-matched water.45 Furry Diary plan
Can a Bubble Eye Goldfish live with others?
Yes, it is sociable and does best with other gentle, slow-swimming fancy goldfish like bubble eyes, celestials, telescopes, and Black Moors. Avoid boisterous fish. A group of five or more is ideal.16
How long does a Bubble Eye Goldfish live?
The lifespan of a Bubble Eye Goldfish varies; it is not specified in the provided information. Please ask a good breeder or exotic-pet vet for typical longevity.
Can I handle a Bubble Eye Goldfish?
Handling is not discussed in the provided facts; it is best to avoid handling to protect their delicate, fluid-filled eye sacs. Ask your vet for safe care guidance.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
You might also like
Celestial Eye Goldfish
Telescope Goldfish
Black Moor
RanchuLike what we are building? Buy Archy a bone.
All of this is free for everyone, with a source on every fact, and it will never show annoying ads. It was a big job to build, so if it helped you, buy Archy a bone. Any amount is lovely, and no is a perfectly fine answer too.
Archy is our Australian Cattle Dog and chief taste tester. Tips go to 4V3D OÜ, the small family studio behind Furry Diary.
Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- Bubble Eye - Wikipedia en.wikipedia.orgused for origin, history, body, colours, size, tankmates, decor, fun facts
- Celestial eye goldfish - Wikipedia en.wikipedia.orgused for toadhead ancestry
- List of goldfish varieties - Wikipedia en.wikipedia.orgused for variety status
- Fish environment - RSPCA rspca.org.ukused for tank size, filtration, water changes
- Goldfish Care Sheet - Aqueon aqueon.comused for temperature, tank size, diet
- Carassius auratus - FishBase fishbase.seused for pH, group size, diet, IUCN
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.