nerite snails should be able to live in that, and even breed successfully.
however most of the nerites I've come across are freshwater acclimated, so you'd need to go through a few weeks of snails in a small QT tank, just so you could raise the SG to match the display tanks o they snails didn't die of shock.
I've never run brackish so I can't suggest anything else, but I'm sure there's some crawfish that'd go brackish...whether it'll kill all your fish is the real concern.