Wounded face on bloodfin tetra

Hey, all!
While doing a water change this morning, I noticed that my last little bloodfin tetra didn't look right. Upon closer inspection, it almost looks like he's missing part of his face. I have no idea what may have happened, whether this was an injury caused by another tank mate or if this is disease related. I've isolated him into a quarantine tank just in case it's been caused by disease, and then proceeded with doing a larger water change in the main tank than what I originally started. I've attached some pictures, they aren't the best but I did try. He wasn't very cooperative, haha. What do you guys think? Should I give him the chance to heal in the quarantine tank, or do you think I should humanely euthanize him due to extensive injury/disease? I do not know for certain whether or not he can eat; I fed earlier in the evening and wasn't watching him in particular.
Thanks in advance to anyone able to help!

I would say it has a bacterial infection, which is causing the mouth to erode away and the eyes to bug out. It will probably be dead by tomorrow so euthanise it. monitor the remaining fish and if any show symptoms treat the tank.

Colin_T said:

I would say it has a bacterial infection, which is causing the mouth to erode away and the eyes to bug out. It will probably be dead by tomorrow so euthanise it. monitor the remaining fish and if any show symptoms treat the tank.

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Hey Colin_T, thanks for responding to another one of my posts.
How would you recommend euthanizing?

I would whack it on the head but that's just me. Wrap it in a paper towel and hit it with a hammer or block of wood.