Black Moor with Reddish Sore on Mouth

Question
He shares the tank with a Calico Fantail, a Plectostomus and a smaller Black Moor.  I had another Black Moor who had the same red swelling and it grew larger and he eventually died. I love my fish and I don't want him to die, but I don't know what to do! I'd appreciate any and all help I can get! Thanks!

Here's two pictures I took of him:
http://i30.photobucket.com/albums/c329/xifaur/S5000124.jpg
http://i30.photobucket.com/albums/c329/xifaur/S5000135.jpg


It is a 25 gallon tank and the temperature of the water is 70 degrees. The Nitrate, Nitrite and Ammonia levels are at 0 ppm and there are no traces of chlorine. I change the water often, 25% every two weeks. It has a 30 gallon filter and I've had the tank for about 6 months

Answer
Hi Raul;

I really can't tell anything because the photos aren't very clear. Fish are tough to shoot aren't they?

Since the lesion is red, I would suspect bacterial infection or "sucking" by the plecostomus. Sometimes plecos do that at night. If the sores are in similar size to the pleco mouth, that may be it. Or, it could be a bacterial infection and he needs antibiotic food or "Maracyn Two". It would be best to isolate him for treatment. The other fish don't need medicine and it's much more expensive to treat in a larger tank than in a small isolation tank. You only need a 5 gallon or so, or even a bucket with an airstone. No heater, no filter, and no decorations. Change the water daily right before you add the day's dose of meds. Aquarium salt is helpful too. It helps the fish's slime coat. Melafix is a good product to help him heal too. Salt and Melafix are both natural and very good supports for antibiotics. They just can't treat an established infection all by themselves.

Followups welcome...

At Your Service;
Chris Robbins