Petco dollar per gallon sale is on now, It's a good idea to have a quarantine (hospital) tank. I use a bare 10 gallon just filter, heater and a few rocks. If you have a sick fish it could spread to the other fish in your aquarium. I always place new fish in it for a few days before putting them in the main tank. Also if I notice a fish acting funny I will remove it from the main tank, observe it and treat appropriately