Re:Black Rot on Dorsal Fin

Dear Dodge:

It sounds like he had done a wonderful job of rehabilitating the seahorses you acquired and fattening them up again. It’s great that you are able to train them all to eat from a feeding station so readily and the increase in their activity level is also a good sign. But I am concerned about the fin problem they have developed and that is something that should be treated as soon as possible.

I am less certain regarding what the appropriate treatment should be. It sounds like they have developed a form of fin rot, but the common form of fin rot is due to a secondary bacterial infection and is not highly contagious, and the fact that all four of the seahorses have developed the black rot suggests it may be something more serious. Here is what I usually tell hobbyists who are having problems with fin rot:

Fin Rot

This condition usually begins as a white line along the margin of the fin and, as the infection progresses and the membrane of the fin gets eaten away, the rigid fin rays become exposed and the fin frays as a result. As long as you detect the condition early and begin treatment before the fin is eroded away all the way to the body, allowing the infection to invade the underlying musculature, the chances for a complete recovery are very good and the damage to the fin will quickly regenerate itself once the infection is eliminated. For example, this is how I described fin rot in my old "Step-By-Step Book about Seahorses:"

<open quote>
Fin Rot in Seahorses

"Fin rot is another problem that sometimes afflicts seahorses in captivity. When this happens, the alert aquarist will notice that the fins of the seahorse are beginning to look frayed and ragged for no apparent reason. This damage is most obvious in the dorsal fin, which is almost always the first to be attacked. In its early stages, this disease is evident as a fine white line along the edge of the fin, which gradually advances towards the base of the fin until the fin rays become exposed, protruding like the ribs of a tattered umbrella. If the bacterial rot is left untreated, the entire fin will be destroyed and the body tissues of the seahorse will become infected, at which point it can no longer be saved. Early detection and treatment is crucial for curing fin rot. At the first sign of fin rot, Mildred Bellamy recommends submerging the infected seahorse in a numeral 1:4000 solution of copper sulfate for one to two minutes. As she cautions, fishes undergoing this chemical baths should be watched closely and removed at the slightest sign of distress regardless of how much time has elapsed. A second bath should be administered in exactly the same manner 24 hours later. Along with these chemical dips, she also recommends that the infected fins be swabbed with a good bacteriocidal agent, such as hydrogen peroxide or merbromin (brand name Betadine), three or four times daily for a period of five to seven days. It may also be helpful to gradually lower the specific gravity of the aquarium water to about 1.020 during treatment, since fin rot is sometimes associated with high salinity.

"Providing the fin rot is detected early, or is only a mild infection, seahorses usually recover completely following this regimen of treatment, and the damaged fin will be fully regenerated. Once again, I must stress the fact that the key to recovery is stopping fin rot in its tracks before the bacteria penetrates the tissue and the body of the seahorse becomes infected." (Giwojna, Step-By-Step Book about Seahorses, pp. 57-58) <end quote>

Nowadays, of course, we have much better treatments at were available in Mildred Bellomy days, and I would not bother with copper sulfate at all. Rather, I would recommend treating the affected seahorses with antibiotic therapy in your hospital tank or bucket. For example, Ampicillex is very effective for treating fin rot and should be available from most local fish stores:

Ampicillex – the active ingredient in this medication is Ampicillin Trihydrate, which is a synthetic Penicillin, and a superior antibiotic for treatment of fin rot and stubborn eye and mouth infections. Ampicillin also has effective action against many Fungal infections. As with other antibiotics, use every other day for 5 days (3 treatments are recommended). Will not color water.

Either TMP-sulfa or 4 Sulfa TMP sometimes would also be a very good choice for treating fin rot:

Trimethoprim and Sulfathiazole Sodium (TMP-Sulfa)

A potent combination of medications that’s effective in treating both gram-positive and gram-negative bacterial infections. It exerts its anti-microbial effect by blocking two consecutive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria, making it very difficult for bacteria to develop resistance to the medications. TMP-Sulfa may be combined with other sulfa compounds to further increase its efficacy and decrease the chance of resistant strains developing. TMP-Sulfa will knock your biofilter for a loop, so be sure to use it in the hospital tank only.

These forms of sulfa can be obtained via National Fish Pharmaceuticals at http://www.fishyfarmacy.com/.

In your case, Dodge, the black coloration of the fin rot suggests that it may be fungal in nature rather than a secondary bacterial infection, so the treatment I would recommend is a little different. I recommend administering a formalin bath to each of the seahorses individually and then transferring them to a hospital tank for treatment with Ampicillex, which is effective against both bacterial and fungal infections. Adjust the specific gravity of the salt water in the hospital tank to 1.020 and add enough methylene blue to tinge the water a light blue coloration.

Here are the inspections for administering the initial formalin baths:

Formalin Baths

Formalin (HCHO) is basically a 37% solution of formaldehyde and water. It is a potent external fungicide, external protozoacide, and antiparasitic, and is thus an effective medication for eradicating external parasites, treating fungal lesions, and reducing the swelling from such infections. It is a wonder drug for treating cases of Popeye caused by trematodes, and also eradicates external nematodes.

In my experience, provided it is administered properly, seahorses tolerate treatment with formalin very well at therapeutic dosages. For a long term bath the correct dose is 15 to 25 mg/L. [Note: 25 mg/L equals 1 ml (cc) of 37% formalin per 10 gallons of water.] This is done every other day for 3 treatments.

For a short term bath (dip) the correct dose is 250 mg/L. This would equal 1 ml (cc) of 37% formalin per 1 gallon of water. This should be for about 45 minutes to 1 hour. In my opinion, formalin is a safe, effective treatment for parasitic infections in seahorses providing you don’t exceed these dosages and observe the following precautions for administering the medication properly:

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 go to top Chemical Laboratories. Or whatever brand of formalin is available at your fish store should work fine, Pam.

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 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, Pam, 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, see the following web page:

Click here: KPD-54 Formalin-3
http://www.novalek.com/kpd54.htm

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).

Best of luck clearing up the fin rot on your new acquisitions, Dodge.

Respectfully,
Pete Giwojna