What do you mean by 505 water change ?I can't say I recognize it as anything pathological. Keep the water clean do a 505 water change and thorough gravel vacuuming. Keep the filter clean and watch closely for any changes positive or negative. Report back if anything changes and we can reasses.
What do you mean by 505 water change ?
If so, any treatement ?Could be larval trematodes....more common in fish reared in outdoor ponds, snails and birds are the host animals.....