The general rule of thumb is a specific gravity of 1.024-1.026. So the research you have done has not been in vain. Salinity varies all over the world. IMO the key to keeping things happy and healthy is to maintain a constant and stable environment for them to live. They are already being removed from their habitat, but will adjust and be accustomed to slight differences.

SG can also be measured in PPT (parts per thousand) so the differences can be pretty dramatic.

Hope this helps.