I can't imagine not quarantining fish, regardless of the tank they came from in the store. When I started my pond I went in to Petsmart and told the lady to pick out 10 fish in assorted colors, figuring that I wanted five and half would die. I really didn't even check them out except for asking her to catch one that I thought particularly pretty. By the time I got them home, I could see there were some mistakes, and three fish died in the first three days. Everyone else has thrived. I've bought a couple of other cheapies and they have been fine. All three of the multiple-dollar fish I have bought from Petsmart have had problems. One has been in quarantine for months with recurring parasite problems, and the other two died in a couple of weeks -- about the time all of the other fish in their tank at the store disappeared. The prettiest shubbies I've seen around here have been in Walmart. I bought one and it just gets more beautiful as it grows. This store gets some beautiful fish but you want to get them soon after they arrive.