Sick or getting attacked

[Vincefishguy]

Hello all! New discus fish keeper here and what a adventure its been so fare.

So I have a blue diamond that is staying in top corner and has some funny looking markings on its side.
90% are on his right side and also has damaged fins. Does not look like fin rot but one side fin has a hole in it small and dorsal fins are broken up.
My other 3 discus show no signs of this.

When I feed them they all eat but the blue diamond slowly goes to eat and red malboro chase and nip at him to go back into corner.
Are these markings from attacks or bacteria. Dont want to medicate if not needed.

Water paramaters
PH 6.6
kh 2
ammonia 0
nitrite 0
nitrate <50 as I do water changes every 2 days.

20190122_194855.jpg

[brewmaster15]

Looks like its taking a beating Vince. Those marks look like the scales have been knocked off. I would separate it and let it rest. No meds at this time.

Question though, 50 ppm nitrates is pretty high for discus and odd for the water changes you do.Have you tested your tap water for nitrates? Discus can get skittish above 20ppm .

al