On the one hand I understand the sentiment that, "its just a fish". Some people grow more attached to pets than others and everyone, I imagine, feels a loss of confidence or an uncertainty when they lose a fish. It's different with corals because they die slowly so people see it coming for days or even months in advance and there is some emotional preparation. A fish can die suddenly, even from predation or aggression by a tankmate.
Now I kept individual records (over 6300 fish) of every saltwater fish for a LFS (not where I live now) for 2 and half years. I can't release the name or all the details (proprietary) but I can give some perspective on the problem. This store was by comparison I did to ten other stores, number one in sales in the area and diligently held to what they believed were good fishkeeping practices. This included quarantine of visibly sick fish, immediate removal of dead fish, chemical treatment of all fish-only systems for various diseases, bi-weekly siphoning and scrubbing of algae, weekly 25% water changes for all systems, disinfection of nets between use and massive wet-dry filters and skimmer towers. They receive fish from 5 different suppliers and the quality varied widely. Most fish either died or were sold within two weeks of arrival at the store. Overall for the store 18% of the fish died before being sold. When broken down by supplier, 55% of the fish from the worst supplier died before sale. Only 9% of the fish from the best supplier died before sale. This best supplier brought the fish directly from the airport to the store. As a result of my work the two worst suppliers were dropped. The markup for saltwater was typically triple wholesale price due to having to cover these losses and still break even. This store had rather low prices because they sold a high volume. Mark up for freshwater was only double. I’ve seen mark ups of 4-6 times wholesale at other stores. LFS really made their money on the equipment and supplies not the animals.
Sadly many of the fish you buy are going to die no matter what you do. The best way to get new fish to live is to not buy the ones already “dead fish swimmingâ€Â. If you have seen tens of thousands of fish live or die as I have this is fairly easy but even I guess wrong on occasion. So don’t feel so bad if you get one that dies even though you “did everything rightâ€Â. Survival rates could be much higher with better collection, transport, and husbandry practices and most saltwater fish will live for at least ten years if proper care is given. But the industry won’t change overnight.