Perhaps they’ve just had the will to live beaten out of them during transit. I would buy snails locally, if you can, then give them a long acclimation.Sorry I neglected your first question. Salinity is 35ppm, measured with a refractometer that I recalibrated today before I tested. I tested magnesium too, it’s ~1300. I use Tropic Marin reef pro salt. Did the first water change 3 days before adding the snails.