You are going to have to do a fishless cycling from scratch. Unless you know someone with a brackish tank already, you cannot just transfer media, the salinity will kill the bacteria. As for fish:
Datnoids
Archers
Scats
Monos
Mollies
Columbian Sharks
Gobies
Puffers
Anableps
Some Killies
Mudskippers
Hogchokers
Crabs