i highly doubt any freshwater creature will survive in saltwater, and i personally wouldnt try something out like that since it will kill/harm a creature that has done nothing to you
my opinon, i would get a sally light foot crab, a cleaner shrimp, some red scarlets (more expensive then blue leg hermits and might seem the same but blue legs will attack turbo snails to steal their shell and will attack eachother for bigger shells, my blue leg stole my scarlet's shell and left it to be eaten by my cleaner.. WHILE ITS STILL ALIVE! red legs are more friendly and my opinion better), emerald crabs are friendly, blood/fire shrimp are friendly also. These things are good for cleaning the left over food, shrimps will usually jump out of their rocks just to get that piece of food, very interesting to watch
Coral banded shrimp have been known for grabbing certain fishes and killing it, and have also been known for attacking other shrimps also, its just a warning but some people have had no problems with their coral banded
ArrowCrabs, yes they do clean left over food, but have been known for scareing fish away and would eat a fish if they were able to catch one
Mantis shrimp, stay away from this predator, will kill everything in your tank
Best of luck to you and feel free to ask more questions if you have any
