Need Help-What is this?

[mjg1961]

Just noticed this white marking on the pouch of my male H. Eructus. It does not protrude out from the body and is about 1/4" and "teardrop" in shape. Any idea of what it is and do I need to treat it? He is acting and eating normal. Sorry about quality of picture. Camera in phone not the best.

 

[rayjay]

Well my first thought would be vibriosis.
The camera is good enough to show that the tank isn't as clean as it could be so there is an excellent chance that you have bad bacteria colonies somewhere in the tank that are affecting this seahorse.
I would immediately place it in quarantine and lower the temperature (not too fast if there is a big difference) to 68° to 70° F to slow up bacterial growth if it is. Observe the wound and the eating of the seahorse and be prepared to treat if necessary, usually with a mycin like neomycin, kanamycin or gentamycin along with triple sulpha.
This problem usually arises when out of site deposits of detritus/uneaten food allow for bacterial colonies to grow, especially if the temperature is above 75°F.
Obviously I would be keeping an eye on any other seahorses in the tank, and, I would do a major cleaning to be sure there isn't any deposits remaining to keep the cultures growing.

 

[mjg1961]

Thanks for the feedback. They are actually in a temporary tank right now. I have a chiller and keep the tank around 70 degrees. I can lower some more if that will help.I had to break down my 28G Nano because I could not control the growth of some caulerpa that was on one of the rocks I added to the tank from my refugium for seeding purposes. It was taking over my tank and I just gave up. The temporary tank they are in now is bare bottom and I transferred the old live rock over as well. Tank is not nearly as dirty as picture indicates. Their feeding cup is in the way when I clean and I don't alway remove it when I am cleaning so that corner gets a little dirty. I will take your advice though and clean some more and pick up the medicine. New tank/live rock almost cycled.

 

[rayjay]

Even if the new tank cycles completely I wouldn't put the seahorses in it until the problem has been totally resolved with or without treatment.
Assuming you caught the problem early, the seahorses will probably be feeding normally still, and they most likely exhibit standard habits and have not become lethargic and less responsive, but I would still monitor just home many pieces of food go in the tank and what you have to remove as uneaten. The difference has either been eaten or is hidden somewhere.