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My betta has one eye bigger. Is it popeye? What should I do?

Updated on September 23rd, 2025

Pet's info: Fish | Betta | Male | unneutered | 0.01 lbs

Hello! A week ago I adopted a betta from a local aquarium store. The tank setup I have is a 10gal filtered and heated tank (79f-80f) at 6.8-7ph with a few Marimo moss balls and this single fish. He's very active. I noticed that he has one eye bigger than the other and I'm afraid it is popeye. Does this look like popeye? I believe he looked this way when I got him. There is no cloudiness but his left eye is bigger than the other. I did a 30% water change yesterday. what do I do?

1 Answer

Most Helpful Answer

Todd Cecil

Answered By Todd Cecil

Veterinarian

Published on April 4th, 2019

Thanks for reaching out about Cher and including photos. It does appear as if the right eye is enlarged or protruding. Causes of this can be air entrapment behind the eye (usually a result of a faulty pump), retro-bulbar infection/mass or other systemic illnesses. Test and correct water parameters. A veterinary visit for antibiotics is probably the best advise now.
Good luck.
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