You can also acclimate fish for a lower salinity in QT. Corals may like higher but not fish since they tend to have less stress with lower salinity.
A quote taken from the link below
"For saltwater fish the specific gravity (Salinity) your animals are arriving in will be between 1.019 - 1.022. The lower salinity level means your fish is receiving higher levels of oxygen when it breathes. This is an excellent level to keep your home aquarium at. As a side benefit, at this salinity level your fish are less prone to common ailments such as ich. We highly recommend this salinity level for fish only aquariums."