float, and, if you have time, add small amounts of water at regular intervals. I use a turkey baster to take tank water and squirt it into the bag the fish are in. 10 minutes, anhother squirt.
If it is your own tank water that it is in, you can probably dispense with dumping all the water out, and then dump fish into it's new home.
At this point, I can hardly recommend a quarantine tank more... saved my skin more than once..
Lastly, I'm glad your new fish is apparently perking up. Give it places to hide, dim lights, avoid walking quickly by tank...anything you can think of to avoid stressing him. If it is meant to be, he'll perk up.