Injured firemouth cichlid-can he be put in a 10 gallon?

[Runsoncoffee]

Hi, I’ve got a firemouth cichlid that has been causing some problems in my 75. As in he’s killing a lot of the fish, 6 in the past two months.
On top of this he got into a fight with my other firemouth that resulted in him having a huge bite taken out of his forehead. It’s been several months since that happened, but the wound refuses to heal. He’s also been getting increasingly stressed, making him prone to sickness, hides most of the day, doesn’t eat much, and has become significantly more aggressive to any fish that comes near him.
I want to move him into a 20 long and have that as a permanent home. However, I still live with my family, and they will only allow a 10 gallon. My dad originally said to put him in my 5 gallon, which is obviously too too small.
I want to get him out of the tank, at least temporarily, if not permanently. But I’m only allowed the 10 gallon.
I know it’s not ideal at all, but would it be a better option for all the fish if I put the firemouth in a ten gallon (he’s roughly 5-6 inches)

 

[Akg2021]

It’s every 2 inches per gallon I heard so I don’t see why not some one could correct me if I’m wrong but in my opinion I don’t see why not as long as it’s only him and nothing else

 

[Runsoncoffee]

It’s every 2 inches per gallon I heard so I don’t see why not some one could correct me if I’m wrong but in my opinion I don’t see why not as long as it’s only him and nothing else

It’ll only be him. I need him to de-stress, heal, and stop eating other fish

 

[Aiken Drum]

10g will support your fish from a bioload PoV but wont wont give it enough space to live. As a very temporary quarantine tank you could keep it there, but longer term your fish will suffer. If you cant keep the fish in a suitable home can you rehome it? My LFS gives store credit on unwanted fish, maybe you can find somewhere to take in your fish.