Tiger Barb Head Lesions Identification - Help needed

[SMiCay]

I need help to identify what this could be? I left for the weekend and came back to my tiger bard having this weird lesion on his head suddenly. I’m trying to figure out if this is hole in the head, trauma, or something else. It almost looks like the scales have peeled off and I’m looking at the skin/tissue underneath but it doesnt quite look like an erosive lesion that goes deeper as I’d be expecting. The fish does not seem to be eating as well either, but otherwise acting pretty normal. Maybe a bit spookier than normal, but it would be hard to tell. They are kind of spooky anyways. 

Do note: I do have a crayfish in this tank and while he never bothers anyone, he also didn’t get fed a day or two while I was gone this weekend. I wouldn’t have expected him to do anything since Ive not fed him plenty of other times but I am wondering if trauma by him could be a possibility. Another tankmates are two other tiger barbs, 2 cardinal tetras, and one poor little lone long fin danio. + shrimp, etc. Everybody else is fine. (And I know the stocking is not right on this tank, its a long story, I’ve been working on turning it into a community but have a bad batch of fishstore fish still hanging out in the QT).

Second problem: The QT tank has fish in it (of questionable health) that Im pretty sure this guy could eat? (Small little cardinal tetras and galaxy rasboras). Soo Im not sure where to move him for treatment since I don’t necessarily want to use a whole box of meds on the 29g. I have a lil 3 g tank  that I could probably set up if needed? 

I do keep some meds in stock: paraclense, ich x, maracyn, maracyn 2, prazipro, expel p, aquarium salt. 

aquarium size: 29g planted (with invertebrates) 

water parameters: liquid Api tests

temp: 74*F

pH: 7.4 - 7.6 

nitrates: 5 ppm

nitrites/ammonia: 0/0

buffer:  kH: 60-100ppm (5-6 drops) gH: 140-200ppm (11-12 drops)

 

Oo I do see a small rip in his top fin so trauma and possible crayfish attack might be higher on the list?

[nabokovfan87]

It is definitely hard to say what caused it.  Tiger barbs can definitely attack one another, but I don't think they would attack in that specific location on the body.  Usually the front or sides is where mine would attack one another.

If it was the crayfish I would think you'd see more tissue. 

I would move the fish to a container and treat with the QT meds normally suggested.  Aquarium salt to help the fish with external issues and general recovery, an airstone, Maracyn, and Ich-X.  When the directions for Maracyn call for a water change follow the amount of water specified on the Ich-X (it's slightly more) and then dose in both meds.  I think you'd be treating for bacterial issues in this case and the ich-x is to help prevent a secondary fungal issue.