that is a cool setup. one caution, only a couple species of frogfish stay small and suitable for a little setup, and I don't think any of them are black, A. Pictus comes to mind as suitable for that size tank (wartskinned frogfish) so, your little buddy may be moving to bigger quarters soon.

Do a search on reef central, there has been a very nice long extended thread on frogfish called "The Frogfish Files" for well over a year, successes and losses, and so on.. it's a very good read.