Sos Injured Goldfish Help!

Ok, so today I was at my LFS and I decided to go see the goldfish (not intending to buy one, just look) when to my horror I saw that all the goldfish fins were torn up. I asked an employee and she said they had put a lobster (I am assuming a crawfish) in with them and it was resonsible. All in all they seemed to be doing fine. All but one of them. He had his entire back 4 fins (he is a fantail) torn off as well as his right side fin. He was just bobbing at the top with his head facing down. I had to take him.
Now I have him in a 5 gallon (note: I know this is not suitable long term but he is only the size of my thumb and I need to make sure he can get to his food, he isn't really swimming right now so I am not too worried about swimming room. Once I figure everything out I have a 45 gallon for him with 2 other fancy goldies).
Here is the problem, How do I get him to eat? He can not really get his head to the surface and it takes a lot of energy to swim to the bottom or really anywhere in the tank. I need help. I do not want him to die but I don't know what to do with him or how to help him. Will his fin eventually grow back? Please help.

 

When my fish was severely injured, I put her in a small Tupperware to eat so she had less room to search, and I fed her sibling pellets

 

Also awuarium salt really helps with healing fish injuries

 

Pic, please.

 

Ahhh! yay! I just put some flakes in and turned off the filter so they would not get pushed around. As they started to sink he had a burst of energy and started swimming around and catching the food! and I say 'swimming' loosely, it was more like wiggling.

 

will his fins grow back like my betta fish?

 

That’s why I asked for a pic. It’s hard to tell without looking at them. Sometimes they do and sometimes they don’t. It depends on how much is gone. Best of luck!

 

That’s why I asked for a pic. It’s hard to tell without looking at them. Sometimes they do and sometimes they don’t. It depends on how much is gone. Best of luck!

how do I share a pic with you?

 

Are you on a phone or a computer?

 

If you’re on a phone, just hit the “ upload a file” button next to post reply and then upload a pic from your photos.

 

Please do postva picture. It all depends on how far up the rays were damaged. We can’t begin to guess until we check out the pics. Aquarium salt, mblue will help. I prefer to start with the salt but start with half dose in his qt. Do partial water changes everyday and dose the new water with salt at half dose. Do that for three days. Then you can up the dosage just a bit. Not even 75% yet. But we’ll need pics now and in a few days.