When I had my 125 brackish setup, I have archer, mono, scat, columbian shark. Ananbleps wil be harassed, orange chromides might be eaten. F.W. moray eel is a good choise. If you can get your hands on some target fish or mangrove jack would make a nice addition
Gymnothorax Tile is the most common "fresh water" Moray eel. I have kept this fish for years in a brackish water tank. They get large(mine was 20" befor I sold it). They will not tolerate full salt for very long. A true brackish fish!