Pete Giwojna

Dear hobbyist:

I’m sorry to hear that one of your seahorses has developed a problem with Exopthalmia. It sounds like you did a good job of treating the condition and it’s encouraging that the seahorse’s eyes have now returned to normal. When seahorses develop bilateral Exopthalmia they may go off their feed because it affects their vision and therefore their ability to target prey accurately. Normally their appetite returns again once the swelling has gone down and their vision is no longer affected.

The fact that that hasn’t happened in your case suggests that the Exopthalmia could be a symptom of a more serious underlying problem, which hasn’t yet been fully resolved. If so, the possibilities include a systemic infection of some sort, gas bubble disease, and various environmental factors. I will include some additional information on Popeye later in this post, but the first thing we should do is concentrate on getting the seahorse to eat again so that I can keep its strength up.

I would suggest tempting the seahorse with some choice live foods, and then crippling the live prey to make it easier to target and capture. The most humane way to do this is to cool the live shrimp down so that it’s barely moving when you put it in your hospital tank. Put several feeder shrimp in a small container of saltwater and chill it in your refrigerator or even your freezer until the shrimp’s metabolism has slowed down to the point that they are barely moving. When you’ve done it right and chilled them down sufficiently, their legs will still be twitching and moving around enough to attract the interest of the seahorse and trigger a feeding response, but they will be too lethargic and torpid for coordinated movements or evasive maneuvers. Drop the disabled shrimp right in front of the seahorse one or two at a time and they should be sitting ducks. To save time, you can also accomplish the same thing by removing most of the shrimp’s legs to cripple it and slow it down. The live red feeder shrimp or volcano shrimp (Halocaridina rubra) from Hawaii are ideal for this since they are bite-sized morsels that are easy to swallow.

If you’re out of the room red feeder shrimp, you could try the same thing using the live feeder shrimp from Seawater Express instead. They provide bite-sized white shrimp (Penaeus vannamei) in batches of anywhere from 50 to 1000 each. They are hardy, easy-to-keep and disease free. I recommend getting the smallest of the "Snicking Shrimp" they offer in order to fatten up your finicky female a bit:
Seawater Express Inc.
Organic Shrimp Farm / Hatchery

Or the live Mysis from Sachs Systems Aquaculture would also be a good choice for this. You can obtain 200 live Mysidopsis bahia for $35 from Sachs and your seahorses will love them:


Here is some additional information on Exopthalmia that may help you determine if it was just a symptom of a more serious underlying problem that may require additional treatment:

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. 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).

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 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 3-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.

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).

Okay, that’s the quick rundown on Exopthalmia and the most likely causes for the condition.

Best of luck restoring your seahorse to normal! Here’s hoping that it is soon eating like a horse again.

Pete Giwojna

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