my best advise before you get corys,would be to get a test kit
of your own..a fish shop will often tell clients that their water is ok,
so they get a sale from you.
unless the tank was planted,with such a low bio load i doubt the filter is ready,
i used *cycle* from the fish store to help the filter…some people
don't like it,but i found it made a difference when i was setting my tank up
from new,and i added fish slowly,so the filter bacteria could cope,it's not
been set up long either.
i have a group of 6 bronze,i never see them..however other people
have them,and see them all the time…i have kept pepper and albino
in large groups,and they are fun to watch,i intend to get some again.