Fish Suggestions

[Richer]

I'm thinking about replacing my recently deceased lawnmower blenny sometime in the near future. I will most likely replace it with another LB, but I would like to consider other options. I was over at AI and I saw some neat looking gobies, the orange prawn goby (Amblyeleotris guttata I think?) was my favorite. However, I do have some questions. Do all gobies require a sand substrate? My tank is essentially a BB tank with a few spots of sand here and there. The goby I saw over at AI didn't seem to be burrowing in the sand, nor hiding under the rock that was in its tank, so maybe it doesn't really need a sandy substrate?

If not, what other kind of fish would you suggest? I would like a fish that perches on rocks and is not much of a swimmer.

Display tank is 30 gallons with a 15 gallon sump with a total of around 30-40lbs of rock in the display and sump combined.

-Rich