Stenohaline Species:
A number of organisms are tolerant of a wide range of salinities (euryhaline) but others (usually the fishes) are restricted to narrow ranges and being called STENOHALINE. Stenohaline species can't sustain a wide fluctuation in salt content of water.
Many freshwater animals (e.g., goldfish) cannot live for long in sea water (die in environments of high salinity) and vice versa for the reason of the osmotic problems, they would face.
