Let's be honest here for a few moments. You work in a store that routinely receives fish shipments, my guess is weekly, and expects a revolving door of volume. In other words, every fish should be sold within 1 week of its arrival at the store...at least that is what I was used to. Now, there is no medication that will work in that period of time and without a quarantine system (not just 5 tanks either!) you can bet you will have a revolving door of disease; that's life on the business end. Unless you are performing Hypo. long-term in store (I would not) then leave salinity at an acceptable range (25-30ppt). If you want to treat before animals hit the water, perform a Formalin bath in buckets after acclimation and have an anecdotal copper concentration in the system. I would advise to separate the system so there can be tanks for animals sensitive to copper (i.e. don't dose copper there). If you do not want to use copper then you will have to perform routine Formalin bath or an anecdotal long-term formalin/malachite green combo in the system. For freshwater baths, siphon a gallon of water or less into a bucket, place the animal in the bucket, fill with freshwater until 0ppt. Perform this for 30mins-60mins. Every sp. will have a different tolerance. When you medicate with baths, never walk away!!! Sorry this is kinda quick, short on time. Bottom line is, you are not going to get rid of disease without a designed quarantine system so make the best of what you have to work with.
Oh, and for all those that hate Petco, Petsmart, and other mainstream lfs
', pretty much all lfs
are the same...majority of the fish all come from one area and a handful of major distributors and wholesalers