It depends on how high your salinity is. I had a low level brackish tank with some plants, I kept the salinity between 1.004 -1.008. At this level java ferns and mosses did well for me, they can be found in natural brackish waters. I also acclimated dwarf water lettuce by cutting the roots down to 1/4", sticking it in a fishbowl and slowly raising the salinity over a week or so. Added them to that tank and they did great, any DWL I put in straight without acclimation died. Swords are rumored to survive at low levels but did not for me.