Assassin snails are freshwater. But they could. They will survive, but with a much shorter life span. If you are, make sure to acclimate them to the brackish, or they will die right away because of salinity shock.Anyone know if assassin snails do well in brackish water? My 15 is infested with pond snails...I was thinking I would add three assassin snails to take care of them. Thoughts?