I love my Yellow headed/pearly jawfish. They've already paired up & are living together in the same cave/tunnel. They prefer a bit of sand (not sugar fine) mixed into coarse coral gravel & bits of small shells & rubble for building. Mainly their jumping tendencies are during the initial break-in period before they have their cave built.

My second choice would also be a pistol shrimp/goby pairing.

Gobies - stay away from cute but possibly non-reef-safe clown gobies. Tank-raised Neon gobies are nice & cleaners too (but with a short 1 yr life-span).

Anthony

Whatever choice you make I'm sure you'll get great pleasure out of these little guys.