Can fancy make guppies go in a new tank?

I am studying animal care level 3 including aquatics. Leave the tank for at least a week before you put any type of fish in. Ideally you should leave it longer. You have to leave it so the ph levels are not too high. If you put it in straight away they can die as the acid in the water is too much for them to cope with. Put some live plants in your tank as well as this will help to keep the amonia at the right level! hope this helps somewhat