Not sure this is columnaris. Angels have had white on their mouths about 3 weeks. Treated with Kanaplex in the water for 4 doses. Seachem advised to stop treatment. The fish improved after the first dose then no additional improvement. Changed to 18 days of Sulfaplex. No change. White lesions are opaque, no fuzz or fluff. Tank is 60 gallons with a 55g footprint. pH 7.6, ammonia & nitrite 0, nitrate 5, kh3, gh5. Stock is 3 angels and one bristlenose pleco. A third angel had a tiny white spec on her mouth that disappeared during the Sulfaplex treatment. Pleco seems unaffected. Angels are eating and acting normal. Switching to oxytetracycline flakes unless someone can help me. Don't know what to do.