I've used the freezing water method and its quick better than letting the fish suffer.
He's suffering now he's on his back and darting around the tank.
Not sure how much cloves oil it would take to kill a big fish.
I would phone the vet and see if he could put him down for you.
Not looking good at all i'm afraid.
Would of stood a chance if he went to marks two days ago.
Now he really does sound bad if he's on his back for long periods and darting around the tank.
If he still alive by morning I would take marks offer up and give him a chance.
You have nothing to lose now.
Ok I wish you all the best.
But if he still alive by morning please let mark take him.
Have you sent Mark a PM? If not, I would do so. He may not see your reply here.