Corydora/Hospital Tank Questions

[BettaBabe94]

So when I got my panda corys about a month ago there were 4 decent sized and 2 smaller ones. I just noticed that one of the small ones looks like he might have been bullied a little. He’s lethargic and his tail has a small tear. Im thinking about setting up a “hospital” tank that I could make sure he’s getting enough to eat and put some aquarium salt in it. Since corys are social, should I bring over the other small one with him (perfectly fine, not getting bullied) or should he be by himself? Another idea, should I put him in a breeder box in the aquarium to see if some rest and food will help him? 
Also if I do need to set up a hospital tank, I don’t have an extra sponge filter, can I get away with just putting an air stone in the separate tank?

Edited March 30, 2022 by SinfulBetta94

[nabokovfan87]

As long as the cory has a piece of wood or something to give them a place to feel hidden, a solo cory will manage just fine.

I would look up / purchase a fluval brand hang on breeder box and use that for observation. For a full on hospital tank it does need its own filtration, especially for medications, but if you are just running observation, a hang on box is perfect.