Do a search for Lienardella fasciata, you will find alot of info on them. they are a very pretty fish. But, Even with those big nasty looking blue teeth they are rather passive and shy. Mine was in a 75 for 2 years with a orange spotted sleeper goby, a Fuzzy dwarf lion and a large hermit crab. He did great.
I lost him to the large hermit crab. Then for revenge I let the hermit crab play with a large queen trigger. I learned an expensive lesson.