Please read the following, and the info on the krib page. Maybe show that to your wife as well. Exposing fish to NH3, free ammonia, is like exposing an infant to second hand smoke.
NH3 (free ammonia) is toxic, to all fish, even those known to he less stressed than others. Even small amounts of NH3, and even for short durations. The higher the pH of the tap water, as well as the higher the water temp, the more toxic it becomes. A good article on that subject can be found on the Krib.
https://www.thekrib.com/Chemistry/ammonia-toxicity.html
As far as fish from the LFS, that was just some friendly advice.Personally I would get the tank cycled somewhat, for certain, then start thinking about adding fish. And add bacteria in a bottle while fish are being slowly added. The first time around this didn't end well for the fish.


