Reply To: White clustering growths on seahorse

Pete Giwojna

Dear Joel:

I received the photographs you provided, and after examining the white pinhead spherules, I have narrowed the possibilities down to either lymphocystis or Glugea.

There is no known effective treatment for either condition, unfortunately. Lymphocystis is unsightly, but rarely fatal or life threatening. While it is relatively harmless, Lymphocystis can affect marine fish of all kinds. Lymphocystis most often affects the fins of the fish, and in one of the photos, I can clearly see two of the white spherules on the pectoral fin of the pony.

Glugea, on the other hand, is almost always deadly, with a mortality rate of nearly 100%. However, it is specific to Syngnathids, and should not affect any of your other aquarium fish, with the possible exception of the pipefish.

Time should tell which of these possible afflictions is affecting your pony, Joel. If it continues to survive, eating and swimming, and generally behaving normally, despite the white growths, it is very likely suffering from lymphocystis.

If its condition continues to worsen and it eventually succumbs to the affliction, then it was likely a victim of Glugea.

I will provide you with additional information about both afflictions below, sir.

First of all, here’s an excerpt from an old discussion thread on lymphocystis, Joel:

‹open quote›
Lymphocystis is the most common viral infection of aquarium fish. Although lymphocystis disease has a low mortality rate, it may leave an individual disfigured. This disfigurement can have several consequences. If the gills are affected, the fish can have difficulty breathing. If the lesion is located around the mouth, the fish may have difficulty in feeding or may be unable to feed. In addition, lymphocystis may be complicated by secondary bacterial or mycotic infections.

Lymphocystis is transmitted by direct contact with infected individuals. In aquaria, resident fishes are infected most commonly via the introduction of new infected fish or exposure to fish products that are contaminated with the virus. Trauma to the skin via handling or netting, mating, parasitism, and aggressive behavior accelerates viral transmission among fish. Increased water temperature and stocking density also may facilitate the development of lymphocystis. Visible lesions can develop from 1 week to >1 year following introduction of the virus.

There really isn’t a treatment for it…. and for the most part there isn’t a need to treat either ’cause usually it is benign. But on another note… when my Reidi got sick with tail rot and he went through intense antibiotic treat for a prolonged amount of time, he did immerge from the ordeal spot free. It was weird. None of the treatments were suppose to affect this virus… but they were gone at any rate. [From seahorsedreams at]

i’m familiar with Lymphocystis. it’s viral, and normally affects the fins, altho it can show up on the body. it does not tolerate hyposalinity. the treatment is keeping the fish in a hyposalinity tank for a week or two, depending on the severity of the Lympho. it’s not particularly contagious, nor is it usually life threatening. it just looks ugly.

i had a problem with a lionfish in my FO tank. after treatment, i kept the tank at 1.019 SG just so it wouldn’t return.

hope this helps. [from saxman at]
‹close quote›

the whitish spherules are xenomas or glugeal cysts. In that case, we are talking about an outbreak of Glugea, an insidious disease caused by microsporidian parasites. It is highly contagious and causes a mortality rate of nearly 100%. Here’s an excerpt on Glugea from my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished) which may help you determine if you are dealing with this condition:

<open quote>
Glugea heraldi (White Boil Disease)

White boil disease is an insidious affliction that is specific to seahorses and pipefish. It is fatal, highly contagious, and incurable. In the older literature, Glugea is often referred to as “white spot disease,” since the first outward system is the appearance of tiny white spheres (pinhead to pin point in size) on the skin. Thus, Glugea may easily be mistaken for an outbreak of Cryptocaryon at this early stage of the disease. Indeed, you will sometimes read that Glugea can be treated with copper sulfate. That is untrue; such reports are based on misdiagnosed cases and confusion over which type of white spot disease is at work. Don’t make that mistake. Copper has no effect on microsporidians, which spread from within the host, and Glugea can readily be distinguished from Cryptocaryon as the disease progresses.

The most commonly seen form of this dread affliction is caused by the microsporidian parasite, Glugea heraldi, which may attack any part of the body, including internal organs, depending on how the disease progresses. Spores enter the host after being accidentally ingested while feeding or simply breathing. When it spreads outward, the first symptoms of Glugea are often white spots that merge together and coalesce to form whitish, spore-filled ulcers called xenomas. When the tissue begins to break down and the xenomas rupture, they release new spores that infect additional hosts. This is what makes Glugea so contagious.

When the parasites spread from within, they can attack any of the internal organs. In the initial stages of an internal infection, there may be no outward symptoms and the disease is not contagious. In such cases, the spores will not be released until the fish dies and its body begins to decay.

Glugea heraldi appears to affect Hippocampus erectus only, but it is very likely that other microsporidians infect other seahorse species the same way.

As I understand the progression of the disease, once a spore has been ingested, it attaches to the intestinal wall and penetrates the intestinal lining shortly thereafter, thus entering the bloodstream of the host. Transported via the bloodstream, it may lodge just about anywhere in its host’s body to start the cycle of multiplication and reinfection that eventually affects the surrounding tissue at the site of infection. But the insidious thing about it is that it progresses slowly at first so a healthy-looking seahorse can be carrying the infectious spore in its intestinal tract without showing any overt signs of disease.

The first symptom is tiny white spots that may be so small they are unnoticed initially, or if noticed, may be mistaken for the seahorse’s natural markings; when these tiny spheres are embedded under the skin, there may be no noticeable symptoms until the disease is quite advanced. In later stages, the whitish spheres multiply rapidly and mushroom into the surrounding tissue, causing loss of pigment, and pale patches appear over areas of the body where the seahorse has lost its normal coloration.

The uneven loss of coloration as the disease progresses is very characteristic of Glugea, an insidious microsporidian parasite that is responsible for many seahorse tank wipeouts. Although slow-moving at first, Glugea is virulent and deadly. Glugea is specific for syngnathids — other types of fishes are immune — and Glugea heraldi is specific to Hippocampus erectus. Amanda Vincent’s experience with Glugea heraldi is typical: as I recall, out of a shipment of 76 erectus from Florida Bay, only two survived the outbreak of Glugea (Clifton-Hadley and Vincent, 1989). That’s a mortality rate of over 97% and considered a good outcome — in most cases, G. heraldi is 100% fatal with erectus (Clifton-Hadley and Vincent, 1989).

This is how Mildred Bellomy describes Glugea in The Encyclopedia of Seahorses (Bellomy, 1969): ”Tumor-like growths are familiar disease manifestations to many tropical fish hobbyists and aquarists, as well as many commercial tropical fish handlers and some research scientists. In seahorses, the disease in which such growths are seen is rather inappropriately called ”white spot disease.” In its early stage, extremely small white spheres, frequently no larger than a pinhead but sometimes as small as the point of a pin, will be seen on almost any part of the affected seahorse’s body — the fins, the snout, the crest, the cirri — or embedded beneath the skin anywhere on the tail and/or body segments.

”The term ”white spot disease” seems inappropriate because, within a month to six weeks following their appearance, the embedded spheres actually mushroom into surrounding tissue until, in some fish, almost the entire tail and/or body will be affected. In this stage, the disease no longer is restricted to ”spots (Bellomy, 1969).

”Seahorses have several different infections caused by microorganisms. Such infections may sometimes appear to affect only certain areas of the afflicted fish’s tail, body, or head but often, particularly in the final stages, the disease is generalized, involving not only the skin but also the gills and internal organs (Bellomy, 1969).

”White spot disease is caused by a microsporidian parasite of the genus Glugea, believed to be G. acuta, a parasite that is known to cause a similar, lethal disease in the European pipefish <now known to be G. heraldi in erectus>…microsporidians invade and destroy host cells. Usually, the infected cells are morbidly enlarged due to an enormous increase in the size of cellular components. This is characteristic of host reaction to these protozoan parasites (Bellomy, 1969).

”When a microsporidian spore is taken into the digestive tract of a specific host, the spore’s polar filament is extruded to anchor the spore to the intestinal lining. After a time, the filament becomes completely detached and the sporoplasm moves through the opening thus created. The sporoplasm penetrates the intestinal lining and enters the host’s blood stream or body cavity, eventually reaching a specific site of infection. The cells at the later site are entered and multiplication — at the expense of the host cells — begins. This is called the trophozoite stage wherein the protozoans are active, motile, and feeding. The trophozoite soon becomes what is called a sporont, which produces a number of spores (Bellomy, 1969).

“Some spores seem capable of germinating within the same host’s body. Thus, the number of infected cells in such hosts may increase to an astounding total. The surrounding host tissue degenerates and becomes modified into an envelope or casing, frequently visible to the naked eye. This is usually referred to as the microsporidian cyst or a glugeal cyst in the case of white spot disease. The host fish, if heavily infected, dies as a result of the degeneration of nearly astronomical numbers of cells destroyed in the encysting process (Bellomy, 1969).

“When the site of infection is near the surface of the body, head, or tail, the cyst usually ruptures. Mature spores then are released into the surrounding water and are free to seek out another host. It’s thus easy to understand the importance of isolated infected fish without delay (Bellomy, 1969).

”When the infection is confined to internal organs, the spores remain captive and will not be set free until the host fish expires. On disintegration of the host’s body, the spores are liberated, free to continue their deadly invasion of other fish hosts, becoming the source of one or more new infections (Bellomy, 1969).

”Seahorses with Glugeal infection rarely recover. There is no known cure at the time of this writing although in a few instances, prolongation of life has been claimed with the use of chemotherapeutic baths employing copper sulfate as a sporocidal agent. Some seahorses which seem to improve ultimately succumb to a recurring Glugeal infection, but in a different site, or to secondary bacterial infection. Even when the initial Glugeal attack is weathered, the infected fish seems to be left in a weakened condition that appears to invite attack by other diseases (Bellomy, 1969).”

In short, Glugea is not caused by poor water, dietary deficiencies, or inadequate aquarium maintenance. It is caused by an infectious spore to which H. erectus have no resistance. If your seahorses have not been exposed to the disease, they will not develop Glugea; it is usually introduced to the tank inadvertently in its early stages on a new acquisition that has no obvious signs of disease. The best way to prevent this is to quarantine all new arrivals for a period of several weeks before adding them to your display tank. If they are carrying Glugea, the quarantine period will allow the disease to manifest itself before the healthy seahorses in your main display are exposed to it.

If Glugea does rear its ugly head, you must isolate the afflicted specimen(s) at the first sign of the disease. When Glugea attacks eternally, the infectious spores are not released until the cysts burst. Thus, if you can remove a sick specimen in the initially stages of the disease, before the whitish spots or pimples rupture, you can keep the disease from spreading to the healthy ‘horses. When the disease attacks internally, the infectious spores are not released until the fish dies and its body begins to decompose. In that case, you can stop the infection from spreading by removing any afflicted specimens before they die.

Isolating the ailing specimens as soon as possible is crucial. I learned this the hard way, having had some disastrous losses to Glugea myself over the years. Never buy a seahorse that has suspicious spots, bumps, or ”pimples” anywhere on its body. Beware of such markings when they are not symmetrical — not duplicated in the same place on both sides of its body.

I should point out that although there was hope for the efficacy of copper sulfate in treating microsporidian parasites in Bellomy’s day, we now know copper has no effect on Glugea. In fact, there is no known cure. I have not had occasion to treat Glugea for many years, but if I were to devise a treatment for it nowadays, I would immediately isolate the infected individuals and elevate their water temperature into the low 80’s F, which has been shown to favor the host and destroy the parasite (Fenner, 2000). While holding the patients in isolation under stable conditions at elevated temps, I would then treat them with full strength metronidazole (both internally and as a bath) in conjunction with hyposalinity. I would try gut-loading shrimp with metronidazole to get it inside the seahorses, bathe the external cysts in full strength metronidazole, and hope the hyposalinity might rupture any spores that were released. Such a treatment regimen at least has the virtue of never having been tried before. Fortunately, I’ve never seen a case of Glugea in captive-bred seahorses.

There is a good description of a case of G. heraldi, including photographs of the infectious stages of the microsporidian, in a paper titled ”Parasitic infection of the seahorse Hippocampus erectus–a case report” by Amanda Vincent and Clifton-Hadley which appeared in the Journal of Wildlife Disease in 1989 (Volume 25, Number 3, pages 404-408.) Aquarists with access to a good microscope may be able to compare notes and confirm their diagnosis through a microscopic examination.
<Close quote>

Okay, that’s the quick rundown on Glugea, Joel. If you suspect that is what you’re dealing with, sir, the best thing you can do is to isolate the affected seahorse immediately, if they have not already done so. The prognosis is very poor when dealing with this dread affliction, but you have nothing to lose by trying a treatment regimen such as the one outlined above. If possible, injecting the metronidazole would be a much better method of delivering the medication. With seahorses, this is usually accomplished by administering intramuscular injections of metronidazole at a dosage of 50mg/kg repeated every 72 hours for a total of 3 treatments.

Best of luck treating this problem, Joel.

Pete Giwojna, Ocean Rider Tech Support

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