What I've found is that it doesn't take on a cotton like texture with these smaller fish. I mean you could be right, it may be an injury but I'd be surprised, its very odd looking for it just to be an injury.I see no “cotton” or “wool” like indications. Looks like an injury to me. Columnaris would be low on my list of culprits. Change an extra bit of water for the next few days.
Thanks for the info. What do you suggest as a course of action?Over the years there have been hunderds of threads like this.
Besides the Columnaris strain in Neons we suspect there to be a speciesspecific viral issue. A sort of lymphocystis which also is caused by an Iridovirus.
No scientofic proof but in allmost all cases these mouthulcers seem not (very) lethal, untreatable / incurable and almost only appearing in neons.