Eee! You don't need Vodka; that is extremely painful, and unneeded.
Just take your fish out and place him in a small container half filled with aquarium water. Then, scoop enough water to fill the rest of the container into a container with a lid. Pour in the clove oil (I use the whole bottle since it is small) into the container and shake vigorously until the oil is dispersed through the water. Then, pour this solution into the container holding your fish. He should go still and stop breathing almost instantly. If you leave the fish in for 3 hours and watch for glazing of the eyes, shedding slime coat, and paleness, you can pretty much guarentee the animal is dead. However, if you want to be extra sure, you can destroy the brain after the fish seems "out."