Tilapia rubbed scales off

[Chris Hundl]

I had a dead tilapia with both his left and right side rubbed raw in the same exact spot...is this a sign of a parasite? And if so, does that mean that it can spread to the other fish or is it pretty local to that one fish? There is no sign of any other fish scraping as its been about five days since I pulled this one out.

Ps...the scales were not red like the pictures show while the fish was barely alive...but when he was totally dead and I pulled him out, this is what he looked like...is that blood?

[Steven Gardner]

Wish I had a firm answer for you. I have seen damage like this from excessive aggression. And yes to me that looks like blood.

[Jim Troyer]

looks like aggression to me too. 

You could always add some sea or aquarium salt (no anti-clumping agents) to the system to be sure it isn't a disease.