Help with tetra

[Gorny]

I have a 46 gallon tank with 8 diamond tetras, 6 black phantom tetras, and one large pleco. The water conditions are PH 6.6, amonia 0ppm, and Nitrite 0ppm. The water was changed approximately 3 weeks ago, 1/3 was replaced. There are no chemicals or treatments in the tank. The fish that is ill is one of my black phantom tetras. He has developed a large, red sore on one of his gills. It protrudes out. I have not noticed any other symptoms and none of the other fish seem to have any markings or problems. This is my first big tank and consider myself a beginner. I have placed the ill fish in a separate tank and have added a small amount of aquarium salt. Not sure what to do from here if anything. Could someone please let me know if they can help?

 

[shtinkypuppie]

u mean on top of his gill plate, or in the gills themselves? Ususally cysts like that are bacterially infected somehow. It could be tuberculosis, or some other bacteria i havent heard of. Kanamycin is good for TB, i's put melafix in for anything else. Not sure if they're compatible, if not, go with kanamycin.