Least Killifish Marine?
Fishes of Texas - Heterandria formosa
I am not sure if it is true, but I read on a few sites that Least Killifish are capable of handling Saltwater. If it is true I might make a tank girl them. I know they can handle brackish water. I know their relatives in the genus poecillia are pretty salt tolerant.
10 gallon planted Least Killifish/Assassin Snail
20 gallon planted Guppy/Assassin snail tank
I use Guppy Grass for the tank and Pothos above.