Newly acquired bristlenose pleco has some sort of wound I'm trying to identify in order to treat. Started off as a small white spot and has progressed to this in about three days time. 20 gallon tall and lives with a Dwarf Gourami and 5 neons. Water parameters are perfect, all other fish appear healthy. I've treated with API general which had no effect. Any ideas on what this might be would be appreciated!