of course ammonia is bad for fish.....
this guy from the store is really learning...bofff
the use of cycle may help......and as ronrca said
if you wait 1 or 1.5 week you can make them crazy
i used that once and was fine.....
tip: if you wanna test the guy, ask him about the behavior
of some pair of species that you may know and check...
just buy him fishes if they look good and cheap....