Bleeding?

[unknown_7]

This sounds and looks kinda weird, but I noticed today that one of my albino tiger barbs has this big red mark around the mid-posterior area, close to the base of its dorsal fin. It kinda looks like when you have a cut that was bleeding, but has stopped bleeding, yet is still REALLY red.

I was wondering what this could be?

 

[Zagz]

Perhaps a nip mark from the other barbs?

 

[unknown_7]

I hope not. the thing though is that this mark is visible on both sides of the fish at the same place and looks exactly the same.