There are so many things that contribute to fish casualties with new fish. It used to be that the supply chain kept their salinity at least 1.021 with most wholesalers running 1.025. Now most wholesalers keep their salinity at 1.018 or lower. In fact, salinity levels as low as 1.014 is very common at the So. Cal Wholesalers. Then the stores get these fish and do the typical fast acclimation which results in osmotic shock and a very high percentage of fish dying over the course of a month or so. Add to that, the collection methods, transport and handling etc. The end result is that a very high percentage of collected fish are doomed. Top that off with stores that run low salinity and customers who don't match bag water salinity or those who don't QT and treat fish for parasites and the rest is history.
It's pretty sad in my opinion and I think a big part of the issue is the wholesalers who keep extra low salinity levels in their fish systems. While some would say they do it to reduce parasites and stress, I think a big factor is cost savings on salt or salt water. Having been in the hobby for over 30 years, I can tell you that it used to not be that way. The survival rates were much higher many years back and I honestly believe that a part of the issue starts with the wholesalers salinity and ends with the retailers acclimation methods to this lower salinity water. In fact, most retailers don't even test their bag water salinity and are nieve to the fact that they are taking fish from extremely low salinity levels and acclimating them to 1.021 or high in a matter of an hour or two which just doesn't work.
