Silver Dollar - fuzzy gray spot with bubbles

Question
55 gallon, community tank, 15 fish(small 1" to large 3"), have had same fish for over a year... under-gravel system, 2 aquaclear 30 powerheads, hot magnum charcoal filter, 78 degrees, 1/4 tank water change every 2 weeks.
I just noticed that one of my silver dollars (large 3" fish)has a large (vertical 1/8"x1")gray spot on the body with some bubbles. Looks like fungus/lesion but has a feww bubbles on outer edge? Other fish are attacking him. No one else has symptoms...resembles lesion on blue gourami a year ago (died quickly)

NOTE...I can't really read Spam Guard characters?

I have other questions about strange/changing fish behavior but this is most pressing. Will do 1/4 tank change tonight...not sure whether to add Rid-Ich? Do not have hospital tank.

Thanks for your help.

Answer
Hi Sydna;

I don't think the Rid-Ich will have any effect on this because he doesn't have a parasite. It sounds like an injury that became infected with bacteria. He may even have been burned by the heater and it became infected. Some fish get too close to the heater at night. The medication I would recommend for it is Tetracycline. Also use aquarium salt and melafix. The melafix helps heal and soothe the wounds. The salt gives back electrolytes to treat shock and stress.

He really needs to be isolated somehow so the other fish don't kill him. The antibiotic will also make a horrible mess in your aquarium fi you try to treat him there. You don't have to have an "official aquarium", just a plastic storage container or bucket with a lid that holds 5 gallons or so filled with aquarium water he is already in. Get an air pump and put in an airstone and add a heater. You don't want a filter or any decorations. They will absorb the medication. You will need to change 25% of the "hospital tank/container" water every single day to keep it fresh for him so he can get well. Even while using medication the water should be partly changed every day. Just add the day's dose of medicine right after that day's change.

I hope he feels better soon...

At Your Service;
Chris Robbins