Does my fish have ich or is it just a discoloration?

My black moor has what looks like a powdery look to it... kind of like a dusty white color but you can still tell he's black. It's not bumpy. he seems active except at night when i come home he always rests at the bottom but he's been doing that since i got him a month ago. He's eating fine? I had added a pleco to the tank a week and a half ago so I'm hoping that it isn't ick... I'm going to add some salt and buy ich meds just in case. Please help i don't know what to do.