Hi Everyone! I am new to this form and joined because a couple of my fish sick. Including my favorite large angel. I someone could help me out that would be awesome!
My angel fish that is 2 or 3 years old has a sore on its bottom lip, is swimming diagonally, and has lost its appetite (see pictures below). The tank parameters are 10 ppm
nitrate, 0 ppm
ammonia, 0 ppm
nitrite, and 7.0 pH. The tank has been set up for 2 years and is a 20 gallon. I am using a penguin bio-wheel 100 as a filter. I feed the fish flake food and it is a fully planted tank. I already tried curing the fish by treating the tank with 4 doses of Erythromycin, took out the carbon filter, and did a 20% water change as directed. The angel did not get better and now it seems as if the Barbs are getting red mouths too. It anyone has any ideas let me know as soon as possible so I can treat the tank.