Popeye in Saltwater Aquarium Fish

Causes and Treatment of Popeye in Saltwater Aquarium Fish

Las bacterias se multiplican dividiendose. (Bacteria multiply by dividing.). National Institute of Allergy and Infectious Diseases

 "Popeye" in saltwater aquarium fish, scientifically known as exophthalmos or exophthalmia, is the swelling of the eye, with or without cloudiness, which is caused by the pressure of fluid building up inside the eye itself. The fluid inside the eye consists of white blood cells and fluids. Popeye is actually not a disease but is a condition which is the result of a bacterial infection which can originate somewhere else, other than the eye, in the fish's body. 

Causes of Popeye

Popeye is normally caused by an injury somewhere on the fish's body (usually, but not always to the eye itself) which allows bacteria to enter the fish's body and causing a bacterial infection. In defense, the fish's body produces white blood cells to defend itself against the infection. These white blood cells can migrate to the eye itself and cause it to swell and become discolored.

Quite often, the injury is to the eye itself. The injury can be caused by an "ammonia burn' or a scratch or other damage to the eye. Ammonia is acidic and when high concentrations of ammonia come in contact with the eye for any length of time, the outer layer of the eye can literally be burned off, leaving a large opening for bacteria to enter the eye. Ammonia burns happen most frequently during the cycling period in a new tank when ammonia spikes frequently occur. Frequently, fish are exposed to high levels of ammonia during the collection and transport of wild caught fish. Normally, wild captured fish are placed in containers at sea and then transported to the holding facility before being shipped to their end destination. If steps are not taken (adequate filtration system, frequent water changes, chemical treatment) to eliminate the ammonia produced by the fish, Popeye will be the end result. The damage may not be evident immediately but instead will show up a day or two later. Ammonia burns are not limited to the eye itself, but can also easily affect the gills of the fish.

A symptom of this is rapid gilling when the fish is at rest and not excited by outside stimulation.

Actual physical injury to the fish's eye can have a number of causes, the most frequent of which is scratches to the outer surface of the eye by a net (less than careful netting of a fish with an abrasive net material) or a contact injury from another fish (some dorsal fins have very sharp spines) or from its environment such as live rock in a tank.


The treatment for Popeye is the same as for almost any other bacterial infection which is the administration of a good saltwater aquarium fish broad spectrum antibiotic such as tetracycline, chloramphenicol or kanamycin which will kill the invading bacteria. The earlier the treatment is administered, the better the odds of a full recovery.

Since the antibiotics used for the treatment of this condition can damage the biological filter in a saltwater aquarium, if the other occupants of the show tank do not show signs of Popeye, it is best to remove the affected fish to a Quarantine Tank for treatment.

If the show tank is to be treated, immediately remove any ammonia in the tank with a good ammonia reducer. This will limit the damage being caused and allow the fish to start healing. Once treatment is complete, the addition of a Saltwater Nitrifying Bacteria Tank Starter will help kick start the biological filter.


If the treatment is successful, eventually the eye will deflate but may result in various conclusions.

  • In minor eye trauma situations, the eye will usually return to its normal appearance without blindness.
  • In more serious cases where treatment is not provided or proves to be ineffective, the eye may appear colorless and gray, resulting in blindness to the eye, but is not necessarily fatal.
  • In cases where one or both eyes have sustained severe trauma and treatment is not provided or proves to be ineffective, the eye(s) may burst or disappear altogether. This can be such a traumatic event that the fish may not recover and death will occur.


Since bacteria is the main ingredient in the causes of Popeye, maintaining excellent water quality in the aquarium is of the utmost importance in prevention.

Use the smoothest of net material when netting a fish to avoid scratching the eyes.

If a fish is physically injured, remove it to a QT and treat for infection until the wound has healed.