I'm fairly new to this hobby so hopefully this isn't common knowledge but...
I went to a petsmart a month ago and the tanks were pristine... each tank had only similar fish or the fish together that you typically see in fish stores. Fast forward to last week... I go to look at the
and I notice a high amount of dead fish, and for some reason large goldfish in some of the tanks (from what i noticed the ones that contained the most dead fish).
So my question is if there is any explanation or potential cause for putting the goldfish in with the other fish (not something I have often seen), and would that have anything to do with the higher amount of dead fish that i saw?