Tiger Barb Mouth Chewed Off What Should I Do

One of my Tiger Barbs has had his lower mouth chewed off. There is just a gaping hole. I have put him in a 4l Bowl and added antibacterial medicine but I really don't know how he could eat and don't know what to do now.
Please help
.

 

Pics would help and how did it happen?

 

Pics would help and how did it happen?

Pics would help and how did it happen?

HI JamieLu
Can't seem to post the pic but have put it on avatar if you can see it. I think the other Tiger Barbs must have had a go at him as only have mollies, tetra and corys in the tank

pic

 

Oh man, that's worse then I thought it be. Poor guy! Well, if he made it thro the night, I honestly would euthanize it,but that's just me. Its prob in quite a bit of pain and like u said, I doubt **** b able to eat and live a normal life...but if ur not comfortable with that that's ok to, u can just let nature run its course and see what happens.

 

Looks like mouthrot (bacterial).
I'd euthanise

 

euthanize, doubt its mouth can grow back. otherwise, it'll starve to death.