koi injurred

Question
I have a small koi, about 4" long that went in my bottom drain, down 20' of pipe and into the filter basket upside down and was there for hours until I found him (this has been fixed now).  And he was alive, but not by much.  This was on Saturday, June 25.   I have a hospital tank that has 3 small koi, heated and they are healthy.  However it is heavily aerated and since the sick koi was really tired, I just put him in a 14 gal floating bowl and brought it inside.  I have a tiny filter/pump as well as an air stone in it.  I added melefix and up to .4 salt.  He "rested" for 2 days and now is actively swimming.   I put a buddy in there for him a couple of days ago.   I have treated his wounds with debride ointment 2 days ago and yesterday with bio-bandage.  He has a bad scratch along one side, his tail is really red and he only has about 1/3 of his fins.   He won't eat at all.  But doesn't seem lethargic any more.  It appears that he has many scales missing.   I am really new to treating sick koi.  My questions are:  

What else should I do for him?   

Should I move him into the heated indoor tank?  It is about 9 degrees warmer then the pond where he came from and the small container where he is now.  (the pond and his container is running about 70 degrees.  It is a challenge keeping the ammonia down where he is.      

Should I worry about him not eating?

Should I keep the buddy (another 4" koi) in with him?  They seem to enjoy each other and the new one seems attentive to the injured one.

Do you suppose he will pull through?

Thanks for any help, suggestions and guidance you can provide.

Answer
Dear Dolly,

Thank you for your question and sorry to hear about the injured koi.
However as A not experienced koi enthusiast you are doing perfectly!
I think when the koi is more fine you can try to put him in the quarantine tank.
However monitor him well!
Also let him adjust to the temp step by step.
Best way to go is to keep monitoring him and after A few days treat the wounds again.
The redness can be from stress and therefore the other tank can be more sufficient.
Also some salt in A tank can help "assist" the koi in balancing their "water"balance internal.
However, when medicine put in to the tank the best way is to not use salt to be sure.
The koi not eating is not that of A problem the first days.
A buddy koi in A tank gives the sick koi A more relaxed feeling.
So it will surtain not hurt the sick koi more.
Hope this helps and do not hesitate to contact me again if there is doubt or A veterinarian to assist!

Kind regards!
Raf