Marks on discus. Fighting or disease

[DANNY88]

Hi.

Please could somebody help and tell me if my discus has just got fighting wounds or does it look like start of something bad. My other 5 do not have the same marks. This one had paired and they currently have eggs but he has all these marks on his side. The other discus he has paired with is pecking at the body of it a lot, so I am unsure what is happening2146221463h

[Hollowman]

Poor water quality

[broadfoot]

Hey Danny, what's your water change routine? It does look like this discus is doing really poorly. What percent of the water are you changing each week?