What should I do with my Bumble Bee Goby?

I went to the aquarium store to get brine shrimp for my fish and Ghost shrimp (cuz theyre cute) and I saw the cute little goby and asked the man about him I told him about my tank and he said the fish would be compatible. I trusted this opinion and brought the little goby home. Then I researched him online (i know i should have done that first) and it says that they need to live in brackish water, but the thing is im not sure if my other fish will be ok with the salted water. I have 2 mollies 2 black skirt tetras a neon tetra and a dwarf puffer. What should I do????