I totally agree with this method. I myself tried this to save my fish many times (not the same exact way) but it works sometimes and sometimes it doesn't. It just like when someone passes out and doesn't breath. You can perform CPR and yet the person has a chance to live. It all depends on when the fish actually stopped breathing too. BTW this worked with my oscar and jaguar.
I'd like to note that if the fish you receive is extremely weak, but breathing normally upon arrival, it is best not to do any of this. Turn off the lights, acclimate the fish, and get it in the tank asap. Try not to bother it, and make sure no tankmates are bothering it.
If the fish is hardly breathing(or not breathing?), it is best to use the OP's method. For small fish, it likely will not work. I can imagine the success rate to be very low even for larger fish-but as Rally stated-there is nothing to do lose.
I am thoroughly impressed you succeeded and for both your sakes it was worth the effort. good work. you didn't state what the fish was so I figured I'd throw in the feeder guppy as a tease to see if you would say what it was. it worked and the FH is a beauty
I read also that if you just dip in a 9v battery for a split second it will act the same
the metal things they put on your chest when you die...a defrigrelator? I know thats not the spelling but I hope you get what I mean. I dunno how well it works because I've never tried it but I suppose its worth a shot. Make sure the fish is in water while you try it.
Amaroq, using a 9v battery as a defibrillator is usless, as a defibrillator is used to send an electrical charge across the heart of a person, not to shock their whole body - as what you suggest would do, which would just "cook" the fish - this is also why drowned people are first dried off, because the charge is deminished and the displacement that occurs from the body being covered in water.
I'd suggest that instead of the air pump you use an oxygen cylinder instead (they come in all sizes, and in fact the M2 - which is the smallest - will last for 2 hours and you can buy for about $30) as the high concentration of O2 would be more useful than just pressurizing the surrounding air (which only has 20.9% O2 in it). All in all though, the rest is sound.
I revived my Pacu when it jumped out of my tank. But i just dunked him in the water a few times and put the return from my canister filter in its mouth.