I’m very sorry to hear about the problems you are having with your Hippocampus fuscus. They are among my favorite seahorses and are very hard to come by here in the US. If the only seahorse that has developed ulcerations or open lesions is the male that was stuck between two rocks and may have injured himself, leading to infection at the sight of his wounds, then I do not think you are dealing with Vibriosis. With Vibrio infections, also known as marine ulcer disease, we expect to see those open sores and bloody lesions in most all of the affected specimens.
The condition you are describing sounds more like White Patch Disease or Marine Columnaris, which is a different type of bacterial infection caused by Myxobacteria. A white, slimy coating and/or white lines are strings on the body are very characteristic of this condition, and the whitish coat is most often seen on the head or tails of the affected individuals. It is sometimes referred to as "bacterial fungus," and indeed Myxobacteria infections are often confused with fungus although they are caused by gram-positive bacteria. Here is some information about this affliction from my new book on seahorses (Complete Guide to the Greater Seahorses):
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).
These bacteria are typically associated with stress, and columnaris is very often associated with a sudden rise in temperature. It is frequently seen in temperate seahorses suffering from heat stress or among tropical seahorses that have been subjected to a temperature spike during a summertime heat wave (Giwojna, Nov. 2003).
This is primarily an epithelial disease that often presents as a grayish white film that spreads over the fish’s skin, particularly on the head region (Giwojna, Nov. 2003). The whitish plaques spread by radial expansion and may penetrate into deeper tissues, becoming yellow or orange due to masses of pigmented bacteria that stack up in columns forming the haystacks that are characteristic of the condition (Basleer, 2000).
Columnaris is often described as a milky, slime-like film that can be observed with the naked eye (Giwojna, Nov. 2003). The bacteria are actually pale yellow, and the whitish skin lesions may become yellowish or even orange as the bacteria pile up (Prescott, 2001b). Depending on how many layers of Myxobacteria are stacked up in any given area, this gives the fish a patchy white to yellowish appearance (Giwojna, Nov. 2003). These bacteria produce enzymes that can dissolve the skin and decay the underlying musculature.
Hobbyists most often refer to marine columnaris as White Patch Disease and it is often mistaken for a fungal infection (Giwojna, Nov. 2003). Although the head and eyes are most often infected, the slimy white patches can appear anywhere on the body and, in seahorses, the tail is also often affected.
Columnaris infections vary greatly in virulence depending on the strain involved and the conditions that contribute to the disease (most notably water temperature), and the symptoms of the disease can vary accordingly (Giwojna, Nov. 2003). There is an acute form of the disease that may kill very quickly when the head is involved, often within 24 hours of the first symptoms.
Less virulent forms of columnaris allow time for the symptoms to be recognized and treated. For example, milder strains may produce localized shallow ulcers where the white patches first appeared that respond very well to prompt treatment with the proper antibiotics (Giwojna, Nov. 2003). The gills are another common site of infection and are sometimes the only affected area. Respiratory distress may be the only symptom in such cases, and if the gills are examined, excessive amounts of mucous are to be expected (Giwojna, Nov. 2003). Damage to the gills from these bacteria is evident as brownish dead patches of tissue that are often attacked by secondary fungal infections (i.e., Saprolegnia; Prescott, 2001b). Cases of columnaris involving the gills typically respond favorably to nifurpirinol (Giwojna, Nov. 2003).
Affected fish will become very listless and lethargic in the later stages, with reduced eye movement in seahorses (Giwojna, Nov. 2003). Reluctance to feed is very typical and the fish will often exhibit labored breathing due to the involvement of the gills (Prescott, 2001b).
If caught early and treated promptly, antibacterial compounds are often effective, especially when accompanied by a decrease in water temperature. Some of the effective medications for treating columnaris include oxytetracycline (administered orally) and especially combination sulfa drugs that include trimethoprim or neomycin combined with various sulfa compounds (Giwojna, Nov. 2003).
But the treatment of choice for marine columnaris infections is neomycin combined with nifurpirinol (Giwojna, Nov. 2003). Neomycin-nifurpirinol is a potent combination that works synergistically to great effect against this disease (Basleer, 2000).
Columnaris is often associated with temperatures that are elevated beyond what is normal, or exposure to a sudden rise in temperature, and both the mortality and acuteness of the disease will increase at higher water temperatures (Giwojna, Nov. 2003). As with other bacterial infections, stress plays a critical role in the initiation of columnaris disease. Aside from heat stress, other risk factors for columnaris include physical injury, low dissolved oxygen levels, crowding, organic pollution, parasites, and high nitrite levels (Prescott, 2001b).
At the first sign of White Patch Disease or Marine Columnaris, I recommend treating the affecting seahorse(s) immediately in a hospital tank using neomycin together with nifurpirinol (Giwojna, Nov. 2003). Drop the temperature in the hospital tank during the course of the treatments. Reducing the water temperature will slow the metabolism and reproductive rate of bacteria in general, making them easier to control, and the virulence of columnaris, in particular, is markedly reduced at lower temperatures (Giwojna, Nov. 2003).
As with marine ulcer disease, there are a number of parasitic infections that can easily be mistaken for columnaris. Brooklynella, Costia and Uronema parasites all cause cloudiness or turbidity of the skin accompanied by heavy mucous production in their initial stages, which are similar to the white patches and filmy appearance of a columnaris infection (Giwojna, Nov. 2003). In their later stages, these parasitic infections result in respiratory distress and ulcers or open sores that are very like the symptoms of columnaris when the enzymes the bacteria produce erode away the skin and the gills are involved (Giwojna, Nov. 2003). Parasitic infections are often followed by secondary bacterial/fungal infections, and such parasites are one of the stressors that can result in a columnaris infection. This can make it difficult to determine whether you are dealing with columnaris, a parasite problem, or a mixed infection (Giwojna, Nov. 2003).
For that reason, I recommend that you treat for parasites at the same time you are administering neomycin and nifurpirinol to combat columnaris. In other words, combine your antibiotic therapy with hyposalinity in the hospital tank (lower the specific gravity to 1.011), or with daily applications of merbromin, or medication with metronidazole, or all of the above, as explained for treating marine ulcer disease (Giwojna, Nov. 2003).
Once it’s established in the aquarium, columnaris is highly communicable, as are parasitic infections, and it is very advisable to clean up and sterilize the main tank as best you can while the affected seahorses are undergoing treatment in the hospital ward (Giwojna, Nov. 2003). Combine a 25%-50% water change in your main tank with a thorough system cleaning as previously described (Giwojna, Nov. 2003). [End quote.]
As you can see, Elina, you have done very well thus far with the first aid measures you have take. It was very wise if you to drop the temperature of the aquarium is to attempt treating the affected specimens with the medication containing nifurpirinol.
In your case, however, because your seahorses have been battling this problem for some time now and all of the fuscus seem to be affected to one degree or another, I recommend you treat your H. fuscus with a combination of antibiotics, further reduce the water temperature to 68°F if possible, and administer a formalin baths (see instructions below) every other day for total of three treatments.
The antibiotics I recommend for this are nifurpirinol (the active ingredient in Furanase) and neomycin sulfate, but these may be difficult for you to obtain in Germany. If so, then I suggest you try Neo3, which is available online from the following web site:
Click here: AquaBiotics.net
Formalin baths used in conjunction with these antibiotics will help eliminate any ectoparasites or secondary fungal infections that may be involved. Formalin is basically a 37% solution of formaldehyde and water. It is a potent external fungicide, external protozoacide, and antiparasitic, and seahorse keepers commonly use formalin to cleanse new arrivals of ectoparasites during quarantine. Formalin (HCHO) is thus an effective medication for eradicating external parasites, treating fungal lesions, and reducing the swelling from such infections. As such, formalin baths combined with the antibiotics recommended above can be highly effective in treating White Patch Disease or Marine Columnaris when treatment is begun during the early stages.
Many commercial formalin products are readily available to hobbyists, such as Kordon’s Formalin 3, Formalin-F sold by Natchez Animal Supply, and Paracide-F, sold by Argent Chemical Laboratories. Or whatever brand of formalin is available at your fish store should work fine, Elina.
A formalin bath simply involves immersing the seahorse in a container of saltwater which contains the proper dosage of formalin for a period of 30-60 minutes before transferring it to your hospital tank. Include a hitching post of some sort in the container and follow these instructions: place the fish in a three-gallon bucket or a similar clean, inert container containing precisely one gallon of siphoned, aerated tank water. Medicate the bucket of water with with the appropriate amount of formalin for a concentrated bath according to the directions on the label. Place an airstone in the bucket and leave the fish in the bath for 30-60 minutes. If at any time the fish becomes listless, exhausted or loses its balance, immediately place the fish in clean, untreated water in your hospital tank.
I want you to be aware of these precautions when administering the formalin bath:
Formalin has limited shelf life and degrades to the highly toxic substance paraformaldehyde (identified as a white precipitate on the bottom of the solution); avoid using any formalin product which has such a precipitate at the bottom of the bottle.
Formalin basically consumes oxygen so vigorous aeration must be provided during treatment.
Time the bath closely and never exceed one hour of chemical exposure at this concentration.
Observe the seahorse closely during the bath at all times, and it show signs of distress before the allotted time has elapsed, remove it from the treatment immediately.
If you can obtain Formalin 3 from Kordon at your LFS, Elina, these are the instructions you should follow for your formalin dip:
METHOD 2 (DIP) FOR THE PREVENTION OR TREATMENT OF FISH DISEASES
(a) To a clean, non-metallic container (i.e., a plastic bucket), add one or more gallons of fresh tap water treated with Kordon’s AmQuel . For marine fish use freshly prepared saltwater adjusted to the same specific gravity (or salinity) as in the original tank. Make sure the temperature in the container is identical to that in the aquarium
(b) Add 1 teaspoons of Formalin·3. This produces a concentration of 100 ppm. formaldehyde.
(c) Agitate the solution with an airstone and adjust for a moderately strong flow of air.
(d) Remove the fishes to be treated and deposit them in the container for a treatment period of not more than 50 minutes. Immediately after the treatment period, or if signs of distress are noted, remove the fishes to a previously prepared recovery tank. The fishes may be returned to their original tank, but the presence of the original disease-causing agents in the tank water may result in a reoccurrence of the disease condition.
(e) Observe recovering fishes. Make sure that tankmates do not molest them during recovery.
(f) Repeat treatment as needed, every week. Each treatment is very stressful to the treated fishes. Do not reuse the dip solution.
For additional information on treating fishes with Formalin 3 by Kordon, she the following web page:
Click here: KPD-54 Formalin-3
If you get another brand of formalin, just follow the instructions that it comes with for a concentrated bath or dip (not prolonged immersion or a long-term bath).
Be sure to observe the following precautions when handling your seahorses for the formalin baths, Elina:
I do not like to use an aquarium net to transfer or manipulate seahorses, since their delicate fins and snouts can become entangled in the netting all too easily. I much prefer to transfer the seahorses by hand. Simply wet your hand and fingers (to avoid removing any of the seahorse’s protective slime coat) and scoop the seahorses in your hand. Allow them to curl their tail around your fingers and carefully cup their bodies in your hand to support them while you lift them out of the water. When you gently immerse your hand in the destination tank, the seahorse will release its grip and swim away as though nothing out of the ordinary has happened.
Composed of solid muscle and endowed with extraordinary skeletal support, the prehensile tail is amazingly strong. Indeed, large specimens have a grip like an anaconda, and when a 12-inch ingens or abdominalis wraps its tail around your hand and tightens its hold, its vise-like grip is powerful enough to leave you counting your fingers afterwards!
In fact, it can be quite difficult to remove an attached seahorse from its holdfast without injuring it in the process. Never attempt to forcibly detach a seahorse from its hitching post! When it feels threatened, it’s instinct is to clamp down and hold on all the tighter. When you must dislodge a seahorse from its resting place for any reason, it’s best to use the tickle technique instead. Gently tickling the underside of the tail where it’s wrapped around the object will usually induce the seahorse to release its grip (Abbott, 2003). They don’t seem to like that at all, and will quickly let go to move away to another spot. Once they are swimming, they are easy to handle.
Antibiotic therapy combined with daily formalin baths should be very effective in getting this problem under control, Elina. Hopefully, your seahorses’ appetites will return to normal once this infection is under control. If not, there are other measures we can take to get them eating again.
Best of luck with your treatments, Elina!