Re:Seahorse swollen eye

Pete Giwojna

Dear Judy:

I’m sorry to hear about the eye problem your female seahorse has developed.

That bubble-like protrusion of the eye sounds very much like Exophthalmia, a condition commonly known as Popeye for obvious reasons. The most striking symptom of this malady is that one or both of the eyes enlarge and bulge out of their sockets as if under pressure. The affected eye(s) look as though air or fluid is building up within, around, or behind the eyeball. In severe cases, the eye(s) can become enormously, grotesquely swollen, and vision or depth perception is adversely affected (especially when both eyes are involved), making it difficult for the seahorse to accurately track and strike at its prey. When the swelling is doughnut shaped, that can be an indication that a bacterial infection is at work, but as long as you have the Diamox (tablet form of Acetazolmide), it doesn’t really matter whether an infection or a gas emboli or both is the cause of the problem — Diamox is compatible with antibiotics and you should be treating your seahorse with the Diamox and a good broad-spectrum antibiotic as soon as possible. (Even when GBS is not a component in the genesis of the Popeye, Diamox is still very useful in reducing the swelling because of its ability to control intraocular pressure and fluid buildup.)

You have probably already seen the following information when searching through discussion threads, Judy, but I will repeat it for the sake of thoroughness anyway, and then discuss the proper treatment regimen for the Diamox later in this post.

Popeye can result from a number of different causes, and the treatment varies accordingly, as described below:

Popeye (Exopthalmia)

I have seen a number of cases of Exophthalmos or Exophthalmia, more commonly known as Popeye, in seahorses over the years. It is not so much a disease as a condition or syndrome, and like GBS, when it crops up, it is often an indication that there is something amiss in the aquarium (Giwojna, Aug. 2003).

We have already described the enormously enlarged, bulging eyes that are so characteristic of this disfiguring affliction in the section devoted to gas bubble syndrome. When both eyes are affected (bilateral Exopthalmia), vision and depth perception is adversely affected, making it difficult for the seahorse to accurately track and strike at its prey (Giwojna, Aug. 2003). This may leave the affected seahorse unable to feed.

Popeye is ordinarily not at all contagious, and there is typically no danger of it spreading to the rest of the herd (Giwojna, Aug. 2003). As described below, a number of physical injuries, environmental factors, noninfectious and infectious diseases can cause Popeye to develop. In my experience, it can be the result of eye trauma, parasitic infestation, gas embolisms forming in the choroid rete behind the eye (a manifestation of Gas Bubble Syndrome), and rarely as a symptom of internal infection (Giwojna, Aug. 2003).

Eye trauma: eye trauma can result from a scratch, scrape or bruise to the eyeball suffered during fighting, netting, handling, or swimming (Giwojna, Aug. 2003). In seahorses, it most often results when rival males snap at one other while competing for mates. When snapping at its adversary, a male will incline his head towards his rival and point his tubular snout directly at him, lining up his victim in his sights exactly as if staring down the barrel of a rifle. Once satisfied with his aim, the male will cock his head downwards and pull the trigger, delivering a sharp blow with a powerful upward ”snap” of its snout (Giwojna, Aug. 2003). The snap is usually directed at the gill cover or eye of the opponent — the only vulnerable spots or chinks in an armor-plated adversary’s exoskeleton (Giwojna, Aug. 2003). This maneuver looks as though the aggressive seahorse is headbutting its rival.

Eye injuries from sparring seahorses are uncommon, but they have certainly been known to happen, as I have personally witnessed on a few occasions. Suspect eye trauma as the cause of the Popeye when only one eye is affected (unilateral Exopthalmia) and the water quality and aquarium parameters check out fine (Giwojna, Aug. 2003). Surprisingly, when Popeye results from eye trauma, the seahorse often appears relatively undistressed by its bulging eye and grotesque injury (Giwojna, Aug. 2003). It often remains in good appetite, eats well, remains active, and generally behaves as though nothing out of the ordinary has happened (Giwojna, Aug. 2003). It may continue to court or even mate in spite of its condition.

In such cases, the Popeye will often resolve itself if the seahorse is left to its own devices in the display tank and the injury is allowed to heal on its own (Giwojna, Aug. 2003). Attempting to net it or otherwise remove the seahorse for treatment risks further aggravating the trauma or causing additional irritation to the eye. The enlarged eye will deflate as the injury heals, which may take anywhere from several days to several weeks depending on the severity of the trauma (Giwojna, Aug. 2003). In minor cases, it’s best just to let the seahorse be.

However, as with any such injury, there is always a danger of secondary infections. To protect the seahorse against such complications, consider bioencapsulating or gut-loading live food (adult brine shrimp, red feeder shrimp from Hawaii, ghost shrimp, etc.) with a good broad-spectrum antibiotic such as doxycycline, kanamycin, minocycline, or nifurpirinol + neomycin and continue feeding the medicated shrimp to the seahorses until the eye has healed (Giwojna, Aug. 2003).

Ectoparasites (monogenetic trematodes): these nasty parasites head right for the gills and eyes and cause many cases of Popeye in marine fishes, including seahorses. Both eyes are normally infested and the cloudy eyes that result are a dead giveaway that eye flukes or trematodes are involved (Giwojna, Aug. 2003). This was a common problem when the only seahorses available were wild specimens obtained from your local fish store (LFS), but the advent of captive-bred seahorses has greatly reduced the incidence of such cases. If you keep captive-bred seahorses that you obtained directly from the breeder, you will probably never see a case of Popeye caused by trematodes. If you get your seahorses from the LFS, then trematodes need to be considered as a proximate cause for any Popeye that occurs (Giwojna, Aug. 2003). It is while they are in the wholesaler’s or pet dealer’s holding tanks that most seahorses are exposed to monogenetic trematodes. When you bring them home and introduce the seahorses into your tank, you are introducing the trematodes to your system as well. Giving new seahorses from the LFS a 10-minute freshwater dip before they go into quarantine can prevent this (Giwojna, Aug. 2003).

Suspect trematodes when both eyes develop Popeye and are cloudy, especially if your seahorse came from the LFS (Giwojna, Aug. 2003). Confirm your diagnosis by administering a freshwater dip to the affected seahorse. The trematodes will drop off their host after 7-10 minutes in the freshwater; they will be left behind in the dipping container, where they will appear as opaque sesame seeds drifting in the water — proof positive that trematodes are at work (Giwojna, Aug. 2003).

If trematodes are confirmed, the treatment for Popeye is easy and wonderfully effective. A concentrated formalin bath will eliminate the trematodes and reduce the swelling almost overnight (Giwojna, Aug. 2003). Treat the seahorse in a hospital tank or a clean plastic bucket according to the bath instructions on any commercially prepared formalin medication. Be sure to use an airstone to aerate the treatment tank heavily throughout the bath (Giwojna, Aug. 2003). Watch the seahorse closely at all times during the bath, and if at any time the seahorse shows signs of stress, becomes listless, exhausted or loses its balance, immediately return it to the display tank (Giwojna, Aug. 2003). If necessary, the formalin bath can be repeated in subsequent days, but one treatment usually works like a charm. When eye flukes or trematodes are the cause of the problem, a formalin bath can produce miraculous recoveries (Giwojna, Aug. 2003).

Gas Bubble Syndrome (GBS): when Exophthalmos or Popeye is related to gas embolisms or GBS, one or both of the eyes may be affected, the eyes typically remains clear, and the aquarium parameters are often off (Giwojna, Aug. 2003). In some cases, small, blisterlike bubbles just beneath the skin (subcutaneous emphysema) will accompany the Popeye(s) elsewhere on the seahorse’s body, especially its head, snout, or tail. The presence of any such external bubbles is an unmistakable indication that the Popeye is a manifestation of GBS (Giwojna, Aug. 2003).

As previously described, the treatment for GBS-induced Popeye is always straightforward: a 7-10 day regimen of acetazolamide baths administered in a hospital tank in combination with a good, broad-spectrum antibiotic to prevent secondary infections, and accompanied by 50% water changes in the display tank as needed to restore water quality (Giwojna, Aug. 2003). GBS-induced Popeye is often associated with dirty tank conditions and poor water quality, and is frequently seen after the biofilter has been impaired for some reason, or when the death of a janitor (a Turbo snail or starfish, for example) goes undetected, resulting in ammonia/nitrite spikes (Giwojna, Aug. 2003). 50% water changes can be repeated daily until the water quality has been restored. Low pH, oh dissolved oxygen levels and/or high CO2 levels, and chronic stress can all contribute to GBS-related Exophthalmia.

Bacterial/Fungal infection: finally, Popeye sometimes appears in seahorses as a symptom of an internal infection such as Ichthyophonus hoferi (fungal infection) or Vibriosis (bacterial infection). In such cases, it’s important to treat the underlying infection and not the symptom (Popeye); the Popeye will clear up on its own once the underlying infection is resolved (Giwojna, Aug. 2003).

Suspect infection as the cause of the Popeye when more than one seahorse is affected or the swollen eye is accompanied by other symptoms associated with such internal infections: swollen body, lethargy, weight loss, lack of appetite (Basleer, 2000). (Other forms of Popeye usually don’t affect the seahorse’s normal behavior or appearance, other than the affected eye or eyes.)

The affected seahorse(s) should be treated in isolation to prevent the possible spread of the underlying infection. If you are unsure whether the underlying infection is bacterial or fungal, a combination of drugs that’s effective against both is a good choice. Such combo drugs are available from fish stores, or you may combine nifurpirinol (Furanase) with neomycin yourself to create your own (Giwojna, Aug. 2003). If you are confident the underlying infection is bacterial, kanamycin (a potent gram-negative antibiotic absorbed through the skin) usually works well (Giwojna, Aug. 2003).

In your case, Judy, since only one seahorse is affected, that suggests that the unilateral Exopthalmia is the result of either a mechanical injury or gas bubble syndrome (GBS) caused by a gas embolism or emboli forming in the choroid rete of the swollen eye. On the other hand, the doughnut shaped swelling around the eye is often seen as bacterial infections such as vibriosis. Either way, you need to treat the seahorse with the acetazolamide (brand name Diamox) in conjunction with antibiotics as soon as possible.

Once the swelling comes down in her eyes and her vision is restored, your female should begin feeding normally again and we can concentrate on fattening her up a bit at that time.

A bare-bottomed, 10-gallon aquarium with plenty of hitching posts will suffice for a hospital tank. Ideally, the hospital tank should have one or more foam filters for biofiltration along with a small external filter, which can easily be removed from the tank during treatment but which can hold activated carbon or polyfilter pads when it’s time to pull the meds out. It’s important for the hospital ward to include enough hitching posts so that the seahorse won’t feel vulnerable or exposed during treatment. Aquarium safe, inert plastic plants or homemade hitching posts fashioned from polypropylene rope or twine that has been unraveled and anchored at one end are excellent for a hospital tank. No aquarium reflector is necessary. Ambient room light will suffice. (Bright lights can breakdown and inactivate certain medications and seahorses are more comfortable and feel more secure under relatively dim lighting.)

So just a bare 10-gallon tank with hitching posts is all you need for your hospital ward, Velinda. No heater. No reflector. No lights. No substrate. You can even do without the sponge filters or external filter in your case, just adding a couple of airstones to provide surface agitation and oxygenation. That’s it.

In a pinch, a clean 5-gallon plastic bucket (new and unused, NOT an old scrub bucket!) can serve as a makeshift hospital tank. It should be aerated and equipped with hitching posts and perhaps a heater, but nothing else. This makes a useful substitute when the Quarantine Tank is occupied or in use and a seahorse needs treatment.

Stay on top of water quality in the hospital tank/bucket with water changes as often as needed during treatment, and redose with the medication according to directions after each water change.

Set up your hospital tank or treatment container as described above, Judy, and fill it with freshly mixed saltwater that you have adjusted to the proper specific gravity, water temperature, and pH. Then transfer the female seahorse to the hospital tank and treat her with a regimen of broad-spectrum antibiotics as soon as possible.

The antibiotics that I find our most useful in cases like this are chloramphenicol, which you will not be able to obtain, and ciprofloxacin or TMP sulfa, both of which can be ordered online.


Manufactured by Eaten Laboratories (Vibriosis and columnaris)

Ciprofloxacin is a synthetic broad spectrum antibiotic that is effective against gram-negative and some gram-positive bacterial pathogems of fish, e.g. aeromonads, flexibacteria, vibrios. Use for: Columnaris infections (Fin Rot, Saddleback, and Black Patch Necrosis Syndromes), Freshwater and Saltwater Furuncolosis (skin ulcers, systemic disease). Because it inhibits unique target enzymes needed for bacterial replication and DNA repair, it may be effective against bacteria unresponsive to other antibiotics.

DOSAGE & ADMINISTRATION: Add one tablet per gallon of water in the hospital tank for a 1-hour immersion bath. Add crushed tablet to some water, then add this suspension to the hospital tank. Repeat every day for 5-7 days with daily water changes after each treatment. Ciprofloxacin chelates divalent cations water hardness (increase dose for marine fish) and high divalent cations in diet. Its activity decreases with high pH (>6.9). It can be bacteriostatic or bactericidal depending on the effective concentration at the target site.

Because you would be using the ciprofloxacin in a saltwater aquarium with high pH, you should double the dose and add two tablets per gallon of water in the hospital tank. After you crush the tablets to a fine powder and dissolve them in a small amount of saltwater, add the resulting solution to your hospital tank for one hour. After the seahorse has been in the medicated water for one hour, change the water in your hospital tank and replace it with freshly mixed saltwater. The next day, crush up two more tablets and dissolve them, and then add them to the hospital tank, change the water after 60 minutes, and repeat this procedure every day for five to seven days.

You can obtain ciprofloxacin for aquarium use online from Vet America at the following URL:

Click here: Aquafish Ciprofloxacin Tablets 250 mg bottle of 30 – 4664

TMP Sulfa (trimethoprim and sulfathiazole sodium)

USE: for treating bacterial infections, both gram-negative and gram-positive. The combination of trimethoprim plus sulfathiazole sodium retards resistant strains from developing. It exerts its antimicrobial effect by blocking 2 consecutive steps in the biosynthesis of the nucleic acids and proteins essential to many bacteria.

DOSAGE: add 1/4 teaspoon per 10 gallons of water every 24 hours, with a 25% water change before each daily treatment. Treat for a minimum of 10 days.

(1/4 pound treats approximately 940 gallons of water.)
*More effective than triple sulfa.

TMP Sulfa is especially helpful when the Popeye is associated with kidney problems.

You can get both TMP Sulfa and many other useful medications online without a prescription from National Fish Pharmaceuticals at the following URL:

Click here: Fish Medications

If you cannot obtain the ciprofloxacin or TMP sulfa, then scour the fish stores in your area and look for in medication that contains minocycline, or kanamycin, or neomycin as its active ingredient. Any of those antibiotics would also be useful. Tetracycline and oxytetracycline will not be helpful in treating Popeye, but most other antibiotics that are designed for aquarium use with marine fish may be worth a try if you cannot obtain the other antibiotics I recommended specifically.

In addition to treating your seahorse with a good broad-spectrum antibiotic, Judy, you should also treat her with Diamox (the tablet form of acetazolamide) at the same time for best results. (Diamox is safe to use in conjunction with antibiotics.)

Acetazolamide or Diamox belongs to a group of medicines called carbonic anhydrase inhibitors.

Carbonic anhydrase is a chemical in the body that is responsible for the production and breakdown of carbonic acid. Part of this reaction results in the production of bicarbonate. Acetazolamide acts to inhibit the action of carbonic anhydrase and thereby decrease the production of bicarbonate

Bicarbonate is required for the production of the fluid that fills the back of the eye (aqueous humour). By decreasing the production of bicarbonate, acetazolamide decreases the amount of aqueous humour produced in the eye. This helps reduce the pressure caused by the fluid within the eye in conditions such as glaucoma in humans or Popeye (Exopthalmia) in fish.

In addition to reducing the fluid build up within the swollen eye, the acetazolamide will also help to eliminate any gas emboli from the choroid rete, which may have triggered triggered the problem in the first place, making Diamox especially helpful for treating cases of Popeye.

This is how to administer the Diamox properly, Judy:

Acetazolamide Baths

The recommended dosage is 250 mg of acetazolamide per 10 gallons with a 100% water change daily, after which the treatment tank is retreated with acetazolamide at the dosage indicated above (250 mg/10 gal) (Dr. Martin Belli, pers. com.). Continue these daily treatments and water changes for up to 7-10 days for best results (Dr. Martin Belli, pers. com.).

The acetazolamide baths should be administered in a hospital ward or quarantine tank. Acetazolamide does not appear to adversely affect biofiltration or invertebrates, but it should not be used in the main tank because it could be harmful to inhibit the enzymatic activity of healthy seahorses.

Using the tablet form of acetazolamide (250 mg), crush the required amount to a very fine powder and dissolve it thoroughly in a cup or two of saltwater. There will usually be a slight residue that will not dissolve in saltwater at the normal alkaline pH (8.0-8.4) of seawater (Warland, 2002). That’s perfectly normal. Just add the solution to your hospital tank, minus the residue, of course, at the recommended dosage:

Place the affected seahorse in the treatment tank as soon as first dose of medication has been added. After 24 hours, perform a 100% water change in the hospital tank using premixed water that you’ve carefully aerated and adjusted to be same temperature, pH and salinity. Add a second dose of newly mixed acetazolamide at the same dosage and reintroduce the ailing seahorse to the treatment tank. After a further 24 hours, do another 100% water change and repeat the entire procedure until a total of up to 7-10 treatments have been given. About 24 hours after the final dose of acetazolamide has been added to the newly changed saltwater, the medication will have lost its effectiveness and the patient can be returned directly to the main seahorse tank to speed its recovery along.

Best of luck treating your female for Popeye and reducing the swelling in her eye, Judy. If she is having difficulty targeting the frozen Mysis, try handfeeding her, placing each of the Mysis directly into her mouth individually until the swelling in her eye goes down and she can feed normally again. Her feeding instincts may take over from there and she will hopefully snick up the shrimp as usual.

Pete Giwojna

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