I know this post is old, but... If u are vegetarian please stop reading.
Myself and my sister have been doing about 20 odd cycling experiments,
We were specificly trying to find out how to cycle a tank from ground zero for newbies or someone who had to nuke their tanks due to snails or disease etc, and they can't seed their tank.
And by far the fastest method of cycling after nuking etc is a dead HEATHY, HUMANELY killed fresh fish. Combined with ammonia.
The reason is obvious, all living breathing fish contain the benificial bacteria in their gut.
Fishless cycling is far safer and kinder to your fish. But it's also faster.
Fishin cycling (I personally believe this to be cruel) works because the fish all ready have the correct bacteria in their gut but it's slower because of water changes.
So by using a dead fish u combine the speed of a fishless cycle with the instant correct bacteria from the dead fish.
Or u can use a dead fresh shellfish must still have intestines.
Notes, don't freeze fish that might kill the bacteria.
Don't boil fish that will kill the bacteria.
Fish must still have intestines.
The fish we used were killed the same day we added to the tank we were cycling.
Same with the shellfish, they were collected from beach killed and put in the tank on the same day.
Most of our tests we didn't use dead fish or shell fish.