Can fish bruise?

[Delphe]

Hello,

When I got my bloodfin tetras one of them had and still have a red spot.
I first thought it was bacterial septicemia and he was going to die soon.
He is still in the tank swimming around and looking active and fed (he is a little bigger) so maybe a bruise he is heeling from?.
The spot seems to be getting darker (meaning not as bright red as it was) but the only think I am sure of is that it is not larger. I have been trying to take a picture but can't, so I tried to draw it (i am not very talented).
Here it is, I would love to have your opinion.
What do you think of that spot?