I just wanted to remind you that one other very important thing you can do to help get your seahorses tale problems under control is to reduce the water temperature in the aquarium or treatment tank is much as possible.
As you know, elevated temperatures increase the growth rate and virulence of microbes, making disease organisms all the more deadly. Research indicates that temperature plays a major role in the regulation of virulence genes (Olin Feuerbacher, pers. com.). As the temperature increases, virulence genes are switched on, so microorganisms that are completely harmless at cooler temperatures suddenly become pathogenic once the water warms up past a certain point. Thus both the population and virulence of the pathogens are dramatically increased at higher temperatures (Olin Feuerbacher, pers. com.).
This is true of Columnaris and certain types of Vibrio, which is the genus of bacteria most often associated with marine ulcer disease. At cool temperatures these bacteria are relatively harmless, but at elevated temperatures they become highly contagious, virulent pathogens that kill quickly. Neil Garrick-Maidment, director of the Seahorse Trust in the UK, reports that he stopped a deadly outbreak of Vibrio among his Hippocampus capensis dead in its tracks and cured the seahorses simply by cooling their aquarium down to 18°C (64.4°F) for a period of weeks. The bacteria simply no longer presented a problem at that temperature.
So raising or dropping the water temperature just a few degrees can make a huge difference. Here are Neil Garrick-Maidment’s observations on the importance of water temperature when treating a Vibrio infection:
I am not sure if it is of any help but I recently had a problem with vibriosis [marine ulcer disease] in Hippocampus capensis coupled with a couple of gas bubbles in the end of the
tail. Having tried a number of treatments in the past that havn’t worked I took
a slightly more drastic approach this time and dropped the temperature from 23°C (73.4°F) down to 18°C (64.4°F) having first isolated the infected animals into a separate
tank. I then left them like this for 4 weeks after which I increased the
temperature slowly up to 21°C (70°F), which it still is. After the second week
the vibriosis had gone completely (and has not returned) and the gas bubbles
were gone after the third week. In all the time the temperature was low the
animals reduced their feeding and it has now increased with the raising of the
temperature and they since gone on to have two broods of fry.
Seahorse Project Co-ordinator
Notice that Neil’s seahorses were suffering from a bacterial infection that caused open ulcers and tissue erosion as well as an external gas bubble disease (subcutaneous emphysema), just like your seahorse, and that he was able to cure both conditions simply by lowering the temperature of his aquarium sufficiently.
Neil was working with temperate seahorses (H. capensis) so he could drop the temperature farther than would be advisable for your seahorses, Shorty, but I think you’re horses should be fine at 19°C-20°C (66°F-68°F) if you can possibly drop the temperature in your name tank that far, and the cooler temperature would be very helpful in knocking out this bacterial infection.
In short, it makes a lot of sense to reduce the aquarium temps while trying to get an infection such as this under control, Michael. Cooling down the microbes and slowing their metabolism and rate of reproduction accordingly can slow any bacterial infection (Giwojna, Oct. 2003).
A simple way to drop the water temp in your aquarium is to position a small fan so it blows across the surface of the water continually (Giwojna, Oct. 2003). This will lower the water temperature a few degrees via evaporative cooling (just be sure to top off the tank regularly to replace the water lost to evaporation). Leaving the light off on your seahorse tank in conjunction with evaporative cooling can make a big difference and help you knock out this bacterial infection (Giwojna, Oct. 2003). Tropical seahorses will be fine as low as 66°F-68°F providing you drop the aquarium temperature gradually.
Best of luck resolving your seahorses tale problems, Michael!