What about these??
Temperature shock method (freezing)
This method utilises the coldest water you can find - a bowl of water that has been placed in the freezer long enough for the surface to freeze is good. The surface ice is broken and the bowl taken to the dying fish.
The fish is then captured and dropped into the freezing water. The difference between the temperature of the tank and the freezing water causes an instant fatal shock to the fish nervous system stopping all organ functions instantaneously - anyone who has found themselves suddenly in water that is much colder than your body temperature will know the feeling when you initially can't breathe (people have died of heart failure under similar circumstances), it is like that but much more severe and sudden.
A variation on this is freezing alcohol (pure or vodka)
Stress is caused in the handling of the fish, but in most of the methods the fish must be handled - however this handling is brief.
Recommended for: tropical fish
Not recommended for: coldwater fish
Humane rating: 100%
Temperature shock method (boiling)
Works in the same way as the above temperature shock method, but involves dropping the fish into boiling water.
The main problem with this is not the effect on the fish, but rather our perception of it. Boiling something is usually for food, and things that are boiled are usually dead (lobster being the exception and falls under this category).
However this method is completely acceptable and humane for coldwater fish.
Recommended for: coldwater fish
Not recommended for: tropical fish
Humane rating: 100%
N.B. Caution should always be exercised when working with hot liquids, surfaces and devices.
Alcohol
As pure as possible - vodka, tequila.
The method is that you have the alcohol at the same temperature as the water in your aquarium - the fish is introduced to the alcohol and immediately becomes overwhelmed by it.
Alcohol works like an anesthetic and is at lethal levels. The fish will instantly be paralysed and unconscious, death follows quickly due to respiratory failure.
An alternative is freezing alcohol as mentioned above - that might, just be overkill.
Recommended for: all fish
Not recommended for: fish who attend alcoholics anonymous
Humane rating: 100%