Can you issolate him, to observe him to see how he goes, if he has cuts on the tail maybe add some melafix to his water, leave him in a quite room and turn lights off so he can calm down.
I really don't know what to say Depending on how bad it is, I would give it a try (to try and help him that is).
If you haven't already done so, take him out and put him in a quarantine tank. Observe and see how he does. Use some anti-bacterial meds to stop infection from spreading / taking place.
A few months ago my Kuhli loach got damaged when I did a gravel vac I thought his back was broken as he had quite an obvious kink in it and couldn't swim at all. He just wriggled all over the place like a madman.
I quarantined and medicated him, but I almost gave up hope as he only marginally improved over a week. In the end I decided to put him back in the community tank (even though at that point he could still not swim properly and had the kink in his back). But low and behold, a few months on and he's as right as rain !
Without really knowing the true extent of the injuries, is hard to advise.
If you do not have a proper quarantine tank you can set up with proper heating etc. it won't help unfortuntately. You are best of to make a decision by closely observing the extent of possibly injuries. What is his behaviour like at the moment ? What can you see ?
I would not put him in a bucket just for observation as it might worsen any injuries and just stress him out. Unless you can pop a spare heater and filter in the bucket too, he will just be sitting in stagnant water that will gradually turn cold
"obvious kink" This is exactly what my shark is like. now he is in a bucket with heater +boxfilter he is hiding in his shealter. What medicine should I give him?
Thanks I just didn't know wat to do. I was thinking about killing him!!!
Do you have any anti-bacterial meds in the house ? If not, I'm really not sure if there is anything you can safely use in the mean time. I'd suggest seeing how it goes. If he is quite obviously extremely distressed and seem to get worse after a few hours, then it might be best to euthanize him. It's a decision you'll have to make yourself based on your observations. I seriously thought about doing the same with my Kuhli loach but just could not get myself to do it. I really thought he was a gonner several times
If you can get to a lfs, get some meds and start dosing. Keep him quiet.
Good luck !