Renee is not cycling tanks, per se- she's testing bottled "instant cycle" products to see if they work like they claim. Some people claim to have used them (some more than once) with great success. With using x-amount of pure ammonia, one may actually see a spike which would be misleading. With adding a fish per the developer's recommendation, the ammonia is "time-released" as it comes from decaying organics, which would give the bacteria time to feed and multiply, and therefore, one should see no measurable spike. However, I do understand the arguments against using fish, hence my suggestion to ghost feed.