Common Eye Disorders in Fish


PetMD Editorial

Updated Aug. 16, 2022

Eye Disorders In Fishes

Eye disorders in fishes can be due to disease, infections, or injury.

Symptoms and Types 

These disorders can cause the eye(s) of the affected fish to display any of the following symptoms:

  • Swelling
  • Enlargement (giving an appearance of a popping eye)
  • Blood in the eye
  • Ulceration
  • Disfigurement
  • Parasites within the eye
  • Abnormality around the eye

A fish’s eye is usually examined with a penlight or a flashlight. These are used to ascertain whether the problem is within the eye or in the area surrounding it.

Eye injuries usually occur during shipping and handling, especially if the fish is struggling. Blood in the eye, however, is generally due to infection or injury.


There are many common eye disorders affecting the fishes. The three main eye disorders in fishes are:

  1. Gas Bubble Disease: This eye disorder is recognized by the tiny gas bubbles found in the cornea – the thin, transparent tissue covering the eye. The fish may also form tiny bubbles in the gills or fins. Usually a gill biopsy is needed to confirm the gas bubble disease. The veterinarian will then recommend appropriate treatment for the fish.
  2. Cataracts: Fishes can also suffer from cataracts, which is a common eye disorder causing the eye lens to become opaque. Cataracts can be due to nutritional imbalance, parasitic infection, and other genetic or unknown factors. Unfortunately, there is usually no treatment for cataracts.
  3. Eye flukes: This is a type of parasitic infection, which is usually seen in fishes found in the wild. An infected fish will have enlarged and cloudy eyes, occasionally with tiny worms also being found in the eye. The fish will generally become blind in the infected eye, and it may develop a cataract, too. Unfortunately, there is no treatment for eye flukes.

Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health