Red Tail Shark dying in front of my eyes
 

My red tail shark is suddenly dying. I know the way a fish acts when they're on their way out, and a few minutes ago i realized that's how he was behaving.. bobbing at the top or in random places, breathing heavy, not active at all. I'm sure there's not much I can do this point, but what i can see on his right side pretty disturbing..
There are 3-4 thin cracks that look almost look like slices on his body. I thought maybe another fish got at him but the cracks run along the lines of the scales, bottom to top.
Does this sounds like some kind of disease?

Hi. What size tank he's living in? IT will be much helpful if you show pictures and maybe show your water parameters?

Also, how big is your aquarium?