Glass Catfish- Bleeding Wound?

I first noticed a small cut (about 1cm) on the body of my glass catfish 2 days ago. Last night the area around it turned reddish!!! (blood?) It was still swimming around actively and looked normal aside from that, so I decided to leave it in the tank. This morning it was lying in the corner of the tank so I fished it out and put it in a salt solution. It still swims about once in a while but then goes back to lie on the base of the container on its side

Should I euthanise it? Or are there other treatment methods I can try? If I bring it back to my LFS would they care to help the fish?

i am guessing it is a cut because it was a line (about 1cm) across its body about 2 days back. It might have gotten infected and thus the red colour last night.

he is in a vertical position now and swimming/resting that way. sigh. i think i will see if he improves after a few hours, if not i'll just have to euthanise him.