Yeah, it claims the fish can go it a tank after 24 hours. I personally think the people that try these product and it works are normally doing a fish in cycle, with hardy fish and get lucky.
Although it does claim this (and I would never do it), I use it (every now and then) to give the bacteria a boost when a new filter first starts up. Reasoning being very simple.
As I said before, I don't use "bacteria in a bottle" products, simply because very few work (with the possible exception of Seachem Stability, I'm testing that currently). Bactozym provides, as they state it, "by creating an ideal environment for new bacteria to grow". It does not state anywhere on the product that it's bacteria in a bottle (or capsule in this case) and although it does state fish can be added in 24 hours, (a major negative point for buying in my opinion).
I cannot stress this enough that I am not an ignorant fish keeper, I've been keeping fish for years now. I've always found the Bactozym speeds up the GROWTH of nitrfying bacteria, it does this is one of two ways, which I cannot test for unfortunately.
1) Provides an environment ideal for bacteria to grow on, I believe they're called hosts in this instance, basically "places" for the bacteria to colonise easier.
2) Breaking down into ammonia, possibly with some spore form of bacteria in them.
I'm currently testing Seachem Stability as they claim to have covered a broader range of bacteria included, all in spore form, kept in that form by a special suspension liquid. Once the liquid is added to the aquarium, it is diluted and therefore the bacteria come out of spore form. I shall be posting my results, but so far, it is incredibly promising, reducing a nitrite spike from 4ppm to 0 in just 48 hours with no water changes.