Hey ive had expierience with a lot of native fish. I live in florida and the best fish ive kept in my brackish tanks are clingfish. They were for some time grouped in the goby familie but they are now thier own family. Very similar to gobies, but they have a much larger suction cup and tend to be a lot flatter. Clingfish are very widespread throughout temperate and coldwater regions. There are even a few tropical freshwater species in the carribean. These fish are fun because they apreciate target feeding and hand feeding. They are basicaly gobies with "flounder" tendancies. I collect mine by picking up clumps of oyster shells, and by looking in beer bottles. They love corrona bottles.
Here are some more cool of the wall brackish/marine species:
Gobies
Blennies are awsome(Ive kept a few, real fun)
Striped Eel Catfish
Many toadfish
Stikleback(Real shy colwater fish that got mixed in with some minnows i bought for bass bait.)
Sea basses(Atlantic Sand Perch might work)
Jacks
Drums
Cardinal fish such as Kaudern's Cardinal would possibly tolerate 1.015
Some rays(Atlantic stingray)poor chioce cause of size 6'
Killifish
Mullet