We loved our pink spotted goby (Pinky). We had him about a year, and he was over 6" long when he finally jumped - yes he was in for a year without incident, that is why i took the cover off. ours ate SF frozen marine mix(or blend, can't recall the name just now) I thought he was a little reclusive, but when he did come out, it was great.
BTW, pod population in our sandbed was high, I only feed 3 times a week, and he did leave GINOURMOUS piles of sand, of course he was a big guy. We also bought a candy striped pistol (named brain, of course) at the same time hoping for a match, but our HUGE serpent star ate him within minutes of getting in the tank. They can pair up with pistols, though.