Need some info on size of tank in gallons or litres, how many fish and which type, plus water stats in ammonia,nitrite,nitrate,and ph.
Mouth fungus can be white to grey patches, or be fluffy looking, also it can look like the mouth is rotting away.
It's a 55gal tank, 6 Giant Danios, 1 blue Dwarf male gourami, 1 common plec (7in), 4 cream-sickle mollies, 8 neons, and 2 australian rainbows. The "growth" isnt fluffy looking, it looks like a.....zit kind of, solid swollen looking thing.
If anything it coulda been a rock...got some in there with slightly "jagged" edges...nothing sharp though. No redness, pure white. on the outside of the lip, and I havent been able to catch the little guy to feel it.