One thing I never understood very well was if a fresh water fish from Petco/Petsmart community tanks could bring in a disease to salt water? Honestly I never acclimated them, since I'd only buy 3 or 4 at a time, and my angler would eat 1 right away. I just had difficulty finding solid evidence on if diseases could go from fresh to salt like that.
Also, if I had to do it over I'd just set up a simple 10g tank and let the mollies breed (Live bearers) and have my own constant supply of food? Just a thought, maybe reducing the transmission of potential Petco diseases...although through the 2 years I had the angler (Edwardo) I never saw any signs of disease.