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Author : Deepak
Article ID : 27
Audience : Default
Version 1.00.01
Published Date: 2011/3/17 3:23:55
Reads : 19121
Disease and Care

Pop eye (Exophthalmia) is a condition or symptom of an underlying infection in eyes rather than a specific disease, and it can be the result of a number of different causes. The eye bulges out in this manner because of fluid build up, either behind the eye or in the eye itself. The first signs of such infection is either one or even both eyes will start to bulge. Slowly with time it can bulge to such an extent that the fish will look really shocking. The bulging eye may have a thin layer of 'skin' around it, this is a tough tissue that covers the eye keeping it in the socket and as the eye bulges it stretches the 'skin' with it. The fish may also get less active and show no interest in food. Fungus infections can show up afterwards.

If this disease is not detected soon after it is caught the fish can lose one or both of its eyes and its eye sight. You can never be 100% sure the root cause of pop eye, however the most common cause of the pop eye are:

• Internal/external injury
• Bad water parameter/ quality (High nitrates/nitrites/ammonia)
• Internal bacterial infections by Exophthalmus and Corneybacteriosis,
• Water contamination (metal or plastic poisoning)
• Unsuitable salinity

Few other less common causes are
• Vitamin A deficiency, tumors and gas embolism
• Gas Bubble Disease: which is caused by a sudden dramatic change in gas pressure in the aquarium. It's caused by excess oxygen in the water, particularly from filters that blow air directly from outside to inside the tank, and from pressurized tap water that did not get mixed. This can also happen by changing too much water at one time or by adding cold water to the fish tank. Gas bubbles form in the fins and skin of the fish. The bubbles look like blisters and are very easy to see.

Pop eye is easy to identify since it causes they eye to swell up and protrude from its eye socket. The eye will also often become clouded. It is possible to guess the cause of the pop eye based on the symptoms.

1. If only one eye is infected, it is usually caused by an injury (due to fighting with other tank mates or accidental injury during tank maintenance or transportation)

2. Pop eye caused by bacterial infection or environmental issues usually affects both eyes.

3. If pop eye on both eyes is followed by a fungal infection, it is usually bacterial pop eye. It is common for a fish suffering from bacterial pop eye to become infected by fungi due to its weakened state.

4. If pop eye on both eyes is not followed by a fungal infection, the pop eye is usually caused by environmental issues.


It is difficult to specify a specific treatment unless the main cause is definitely known. Different types of pop eye require different treatments.


If caused by Injury: Pop eye caused by trauma can often heal by itself if given optimal conditions. Move the fish with pop eye to a tank where it can be alone and won't get stressed by other fish.  Make sure to keep perfect water quality in the tank.  Adding a tablespoon of Epson salt for every 5 gallon of water for at least 3 days (longer if necessary) in your tank may help the recovery by drawing the fluid out. Please note, Epsom salts isn't really salt (sodium chloride) it is Magnesium Sulphate.

If caused by environmental factors: It is very important to improve water quality and other environmental issues to avoid more fish getting sick. Fish will never get well if you don't improve the environment. If water quality is the problem (high nitrates/nitrites/ammonia etc), perform a 50 percent water change as soon as possible and then 15-20 percent water changes 3-5 times per week, until the water readings are correct. Overstocking is a common problem for bad water quality. Another common reason would be decaying dead fish and fish food. The tank should be thoroughly searched for any dead fish and check if you are not over feed.

If caused by water contamination: check for any new items, which was added to the aquarium recently, it should be double checked that it is not poisoning the water or letting off chemicals. Check the quality of the water conditioner ( take good opinion by other aquarists).

If caused by Bacterial infection: Bacterial pop eye can be hard to treat as it is an internal infection and internal infections are always harder to treat than external since it is harder to get the meds to the place where they are needed. Treat bacterial pop eye with a broad spectrum antibiotic. That is usually effective if the infection hasn't progressed too far already. A fish given antibiotics can recover even from severe cases, but the more severe the case is the harder it will be to successfully treat it.

Reference: Fishlore

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Author Thread
Published: 2011/5/7 0:51  Updated: 2011/5/7 0:51
Just popping in
Joined: 2011/5/7
From: Pasadena, CA
Comments: 3
 Re: Pop-eye (Exophthalmia) – A common fish disease
thanks for the info. Needed tips in starting an aquarium in my small house in Virginia. Keep it up dude.

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