Re:methylene blue treatment

Pete Giwojna

Dear Matt:

I’m sorry to hear that some the juveniles have not responded to your treatment measures thus far. As we have been discussing, the sort of symptoms you describe are sometimes associated with ammonia poisoning and/or nitrite toxicity, in which case they will typically respond well to methylene blue. On the other hand, similar symptoms sometimes result from the irritation caused by various ciliates and protozoan parasites, in which case formalin usually produces good results.

I might be inclined to try a stronger dose of methylene blue – in severe cases of ammonia poisoning/nitrite toxicity, seahorses will sometimes respond well to a very brief 10-second dip in concentrated methylene blue – but the dosage is critical for this procedure and I would have no idea how to achieve the proper concentration of the methylene blue using the product that you have.

Otherwise, you might consider treating them with formalin if you suspect ciliates or protozoan parasites may be involved in their problems.

As far as force feeding goes, if you can find a small enough cannula to easily fit into the tube snout of your juveniles, it may be feasible to administer tube feedings, but I have no idea what size of catheter/cannula would be correct for juveniles the size of yours…

Skin scrapes can sometimes reveal ciliates and other protozoan parasites but are more difficult to obtain on seahorses because of their exoskeleton. Skin scrapes are most helpful when there is an open wound or lesion which can be swabbed, as described below:

Skin lesions should be swabbed with a few sterile, wet (using sterile saline), cotton-tipped
applicators and evaluated by wet mount, gram stain, acid-fast stain, and/or Wright-Giemsa stain.
Skin ‘scraping’ is possible but quite difficult in practice due to the irregular surface architecture
of the bony-plated armor. Follow-up diagnostics to the initial skin swab include aerobic bacterial
culture, mycobacterial culture, and cytological exam by a pathologist familiar with fish. Fin clips
can be performed if fin lesions are observed.

You’ll want to acquire some standard microscope slides and cover slips, one or two well slides, and some of the commonly used stains so you can practice doing wet mounts, smears, and staining the specimens you are examining, if you don’t already have them, Matt.

I will list a number of online articles, papers, and books with good photographs that may help you diagnose disease problems with your microscope at the end of this message, sir, but here’s some relevant information from my new book (Complete Guide to Greater Seahorses in the Aquarium, TFH Publications, unpublished) to get you started. (I should point out that these are very brief excerpts which I have limited to the pertinent information that will help you identify various pathogens and parasites using microscopy. The actual discussions of these disease problems in my book are quite comprehensive, with detailed descriptions of the diseases and their symptoms, diagnostic procedures, preventative measures for each specific problem, contributing factors, discussions of treatment options, and complete treatment instructions and protocols.)

White Patch Disease: Myxobacteria (Marine Columnaris)

Marine columnaris is a highly contagious disease caused by a Myxobacterium (Flexibacter sp.) that corresponds to the columnaris infections so commonly seen in freshwater fish (Basleer, 2000). The bacterium Flexibacter is a long, slender rod-shaped organism (0.5- 1.0 microns in diameter, and some 4-10 microns long) that is easily identified under the microscope by its characteristic gliding motion (Dixon, 1999). They are unusually mobile bacteria. They are very active when observed microscopically, gliding rapidly across the viewing field (Dixon, 1999). This family of bacteria (Cytophaga or Myxobacteria) causes a condition commonly known as columnaris because of their tendency to stack up in columns (Prescott, 2001b). When large numbers of the bacteria pile up, they form distinctive haystacks several layers thick where the infection is heaviest (Dixon, 1999).

Marine Ulcer Disease, a.k.a. Hemorrhagic Septicemia, a.k.a. "Flesh-Eating Bacteria", a.k.a. Vibriosis

Marine ulcer disease is a particularly nasty type of infection that most hobbyists have come to know as “flesh-eating bacteria,” and indeed it can often be attributed to bacteria, most notably Vibrio or Pseudomonas species (Giwojna, Nov. 2003). Vibrio in marine fish is the equivalent of the Aeromonas bacteria that plague freshwater fishes (Dixon 1999; Basleer 2000), causing external hemorrhagic ulcers (bloody lesions). Vibriosis is probably the most common bacterial infection of captive seahorses and one of the most difficult to eradicate from your system. Vibrio bacteria are motile gram negative rods, which measure about 0.5 X 1.5 micrometers (Prescott, 2001). When grown on suitable media they appear as shiny, creamy colored colonies (Prescott, 2001).

Mycobacteriosis, a.k.a. Piscine Tuberculosis, a.k.a. Granuloma Disease

Fish tuberculosis is caused by pathogenic Mycobacteria, of which two different species are the primary culprits: Mycobacterium marinum and Mycobacterium fortuitum (Giwojna, Sep. 2003). Unlike most bacteria the plague fish, these Mycobacteria are gram-positive, and take the form of pleomorphic rods that are acid-fast and nonmotile (Aukes, 2004). When cultured on solid media, they form cream-colored to yellowish colonies (Aukes, 2004).

Intestinal Flagellates

Intestinal flagellates are microscopic organisms that move by propelling themselves with long tail-like flagella (Kaptur, 2004). Such flagellates can be found in both the gastrointestinal and reproductive tracts of their hosts. In low numbers they do not present a problem, but they multiply by binary fission, an efficient means of mass infestation when conditions favor them (such as when a seahorse has been weakened by chronic stress), Kaptur, 2004. When they get out of control, these parasites interfere with the seahorse’s normal digestive processes such as vitamin absorption, and it has difficulty obtaining adequate nourishment even though it may be eating well and feeding heavily (Kaptur, 2004). Suspect intestinal parasites are a work when a good eater gradually wastes away despite its hearty appetite (Giwojna, Dec. 2003). Their presence can be confirmed by examining a fecal sample under a microscope, but they can be easily diagnosed according to the more readily observed signs described below (Kaptur, 2004).

The symptoms to look for are a seahorse that’s losing weight or not holding its own weightwise even though it feeds well, or alternatively, a lack of appetite accompanied by white stringy feces (Kaptur, 2004). When a seahorse stops eating aggressively and begins producing white, stringy feces instead of fecal pellets, that’s a clear indication that it’s suffering from intestinal flagellates (Kaptur, 2004).

Uronema marinum

Uronema marinum is the marine equivalent of the Tetrahymena pyriformis parasites that plague freshwater fish (Basleer, 2000). Uronematids are probably the most commonly encountered protozoan parasites of seahorses in the aquarium. They frequently plague wild-caught seahorses and store-bought fish in particular. Unfortunately, they are also one of the deadliest and difficult to eradicate marine parasites.
They live in seawater and normally feed on bacteria and dead tissue, but they are opportunistic invaders that are always on the lookout for food, and are quick to take advantage of weakened fish (Kollman, 2003). It is when conditions favor them and their numbers get out of hand that Uronema becomes a problem. Under those circumstances, they soon begin to attack healthy tissue as well as dead material, invading the gills and muscles, eating red blood cells, and infiltrating the internal organs (Kollman, 2003).
Microscopic examination of skin smears can confirm the diagnosis of Uronema. Under the microscope, Uronema marinum parasites appear as pear-shaped, single-celled ciliates with a single large macronucleus and long hairlike cilia at the rear end (Kollman, 2003). Numerous small (35-50 microns), fast-moving, oval or pear-shaped parasites will appear on skin and fin smears (Basleer, 2000).

Glugea (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-gray, 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.

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.) Hobbyists with access to a good microscope may be able to compare notes and confirm their diagnosis through a microscopic examination.

Amblyoodinium ocellatum (Marine Velvet, a.k.a. Coral Reef Disease)

Marine Velvet is another highly contagious disease caused by protozoal parasites. In this case, the parasites are dinoflagellates and Oodinium is fatal if untreated. These parasites attack the gills primarily, as well as the skin of their hosts, and the fresh-swimming stage of the Amyloodinium protozoans causes massive reinfection of aquarium fishes, leading to death by asphyxiation (Basleer, 2000). Typical symptoms include huffing and respiratory distress, excessive mucus production, and scratching (Basleer, 2000).

Positive identification can be made by microscopic examination. The Oodinium parasites are easily visible on skin or gill smears at a magnification of 100x or 200x power (Basleer, 2000). They appear as dark, cone-shaped unicellular organisms measuring 50-60 microns embedded in tissue (Basleer, 2000).
Cryptocaryon Irritans (Saltwater Ick, a.k.a. White Spot Disease)

Cryptocaryon is another protozoal parasite that invades the gills and burrows into the skin of marine fishes, including seahorses. The life cycle and modus operandi of Cryptocaryon are very similar to that of Amyloodinium ocellatum, so it should not be surprising that it also produces strikingly similar symptoms. Infected fish show labored breathing, excess mucus, and scratch themselves against objects. Along with the characteristic pinhead-sized white spots and excess mucus production, affected fish sometimes show cloudy eyes and secondary infections (Basleer, 2000). The latter can result in skin rot and fin rot accompanied by red or pale patches on the body of the fish (Basleer, 2000).

At 100x magnification, Cryptocaryon parasites can easily be identified in skin and fin smears. They appear as large, dark, bell-shaped or conical organisms measuring about 350-400 micrometers in diameter (Basleer, 2000).

Brooklynella hostilis (Clownfish Disease)

Typical symptoms include turbidity of the skin (a thick, whitish mucus coating in the affected areas), cloudy eyes and breathing difficulty (Basleer, 2000). At first there are no apparent symptoms, but cell division occurs very rapidly and Brooklynella parasites multiply to life-threatening numbers quite quickly in a closed system (Basleer, 2000). These ciliated parasites attack the gills first and then spread to the skin. Clear signs of infection soon appear in the form of respiratory distress and strong turbidity of the skin, often accompanied by excess mucus sloughing in shreds and tatters or hanging off in dark slimy strings (Basleer, 2000). Loss of appetite and listlessness soon follow and skin lesions develop where the turbidity or change in coloration had been, often as the result of secondary bacterial infections. Skin rot and fin rot are common in the advanced stages of Brooklynella. Heavily infected seahorses may die within 24 hours after the first symptoms appear (Basleer, 2000).

The symptoms of Brooklynella are similar to those of other parasites that commonly attack the skin and gills of their hosts. An exact identification can only be made through microscopic examination of the parasites. This requires making a wet-mount of mucus taken from the skin of the infected fish, which can be studied under the microscope. The Brooklynella parasites are heart- or kidney-shaped organisms measuring 50-80 microns by 30-50 microns (Fenner, 2003c). A large oval macronucleus and several micronuclei and other endoplasmic organelles should be visible, as should the hairlike cilia it uses for locomotion (Fenner, 2003c). Another key feature to look for is a prominent adhesion organ on the posterior-ventral area (i.e., located on the underside of the parasite at the rear; Fenner, 2003c). This is the device the parasite uses to attach itself to the unfortunate host.

Costia & Cryptobia

These are flagellated parasites that are commonly found on skin and gills of freshly imported marine fishes (Basleer, 2000). Affected fishes exhibit the usual symptoms of parasitic infection by protozoans, including heavy mucus build up, rapid respiration, loss of appetite, and sometimes darkening or turbidity of the skin (Basleer, 2000). In the latter stages, secondary bacterial infections often taken hold and complicate the picture, causing pale skin patches or red patches, which lead to skin rot and fin rot (Basleer, 2000).

Costia are small, bean-shaped flagellates that are very similar to the Ichthyobodo and Costia sp. that parasitize freshwater fish (Basleer, 2000). Cryptobia are similar in appearance. They are small, mobile parasites measuring about 5-12 microns in length with a long tail (flagella) used for locomotion (Basleer, 2000). Both these flagellates can be readily identified in skin and fin smears using a microscope at 200x to 300x magnification (Basleer, 2000).

Here’s a partial list of books, online articles, and research papers with photographs of disease organisms that commonly affect seahorses and other fishes, which you may be able to identify with a microscope, including pictures of affected fishes showing the characteristic symptoms, Matt:

Aukes, Gary. 2004. Mycobacteriosis. Accessed 24 Mar. 2004. <;
Part of National Fish Pharmaceuticals’ Fish Health Articles:

Basleer, Gerald. 2000. Diseases in Marine Aquarium Fish: Causes, Development, Symptoms, Treatment. 2nd Ed. Gent, Belgium: Blobal Communications.

Dixon, Beverly. 1999. “Bacterial Infections in Fish.” Aquarium Fish Magazine. May/June 1999 (accessed 17 Nov. 2003).

Kaptur, Joshua M. 2002. Internal Parasites and Metronidazole. 4 Dec. 2004.

Kollman, Rand. 2003. “Life.History and Treatment of Uronema marinum.” SeaScope. Vol. 20, Num. 3: 1,3.
Prescott, Shawn. 2001a Diseases in Nature Part 10. Fish Vet: Diseases of Fish. Nov. 2001 (accessed 28 Nov. 2003). <;

Prescott, Shawn. 2001b. Diseases in Nature Part 11. Fish Vet: Diseases of Fish. Nov. 2001 (accessed 28 Nov. 2003). <;

Prescott, Shawn. 2001c. Diseases in Nature Part 13. Fish Vet: Diseases of Fish. Nov. 2001 (accessed 28 Nov. 2003). <;

Best of luck restoring the rest of your juveniles to good health, Matt.

Pete Giwojna

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