Q. I got my 55 all set up over the weekend. Now i just need to add fish. How many are recommended to cycle a 55 tank. I'm not going to keep any of them.
A. A tank isn't just "cycled" or "not cycled"....... it cycles based on the waste load under which it is exposed. So, if you "cycle" it with two goldfish, it is capable of supporting two goldfish. The trick is to establish the beneficial bacteria in the first place. Second, you want to gradually ramp up the waste load placed on the bacteria colony.
So, you cannot cycle a tank with a few fish and then order two dozen of them without serious issues resulting. You will still have to gradually ramp up your stocking levels.
Most people start with the hardiest fish they intend to eventually end up with. For instance, with Central American cichlids, it is possible to cycle a tank first with Convicts. Then one can add a few other fish before eventually adding the more delicate species. It is wise, also, to consider the relative aggression levels of the fish you will be adding (I usually add the gentler fish first).