One of the key features behind the concept of fishless cycling is that one can fully cycle a tank. Whether one uses seasoned media from or has none and must wait longer, the result should still be the same, a fully cycled tank. A fully cycled tank should be capable of handling a full load of fish, but there may be other considerations which may influence how one actually stocks.
-If one knows all their intended fish are compatible and there will not be issues in that respect, fukky stocking can be fine. Otherwise one may wish to stock more slowly in a fashion that is most conducive to "keeping the peace".
-If one is obtaining all their fish from the same source so that they have pretty much all been exposed to the same potential germs, parasites etc., then fully stocking would also be serving as Q for the new fish. If one is obtaining fish from multiple sources, separate Q regimens may be advised, which would mean not fully stocking.
-If one is merely upgrading their own tank(s) to a larger size. Then normally one, knowing their own tank status, knows it is safe to remove fish from multiple tanks and put them all into the new larger one without having to worry about Q issues.
The nice part about fishless cycling is it does offer options. One of which is being able to wait some time after cycling before stocking to decide what to do. The bacteria really are hardier than most think and it is pretty simple to keep them alive and healthy. You just need to feed them a bit. A fully cycled tank can be dosed with a bit of ammonia every 2 or 3 days and the bacteria will stay very happy and healthy and ready to work at capacity on demand. Even if you wish to let a fully tank sit with no ammonia dosing at all, it will stay in decent shape for some time. Days are no issue, weeks would be little issue and once into months one can test their capacity to nitrify just to be sure. You would use the same test you did at the end of the original fishless cycle to confirm the tank was ready. If the bacteria are not fully up to par, it should not take a lot to get them there.
My own experience is that I have set up tanks, some fully or partly planted and some with 0 plants and been able to stock them fully once I know they are essentially "cycled" (I say essentially as it may be a combination of plants and bacteria working together). I have also kept cycled tanks empty for days, weeks or months (in a case or two) and been able to follow the above and fully stock them almost at will.
If you are scientifically minded and would like to see some pretty amazing research on ammonia oxidizing bacteria and how hardy they really are, here is a great study. It is entitled "
Strategies of aerobic ammonia-oxidizing bacteria for coping with nutrient and oxygen fluctuations". It and discusses "
Effects of ammonium and oxygen limitation on the AOB community", "
Effect of ammonium and oxygen starvation on the AOB community" and "
Molecular response of AOB to shortage of ammonium".
It isnt too hard a paper to understand and the best part is it references to about 100 research studies on the topic. You can track down all sorts of research on the subject following the reference links in the study.
Oops forgot the url for that article
http
/onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2006.00170.x/full
