I agree, This is exactly like Petcetera. Petcetera is all ran on the same filtration and everytime I go there most of the fish at least have something minor like fin rot. The best places to go is somewhere you trust (Like a lfs), and somewhere that has seperate tanks and sounds like they know what theyre talking about. Look at all of thier tanks as well, are there sick fish? are the tanks cleaned? it's best for the safety of your other fish to check these things.