For the sake of the fish (any fish, fresh or salt) NO! Imagine living in your closet without every getting out of it other than death.....No room to wander or swim. In your case, walk....your right, it was a stupid question.
I've seen 3 gallon tanks with some neat colorful coral and a variety of shrimp, like maybe 1 coral banded shrimp. I thought about doing that myself but decided to go bigger instead of smaller.
As stupid as it sounds, hermit crabs are a blast to watch. Mine have quite the soap opera going on. I probably have more fun watching the crabs and my peppermint shrimp than anything else in my tanks.