I was reading anarticle in a online magazine (not sure if I can mention it here so I wont), anyways, it was about the shrimp gobies and their symbiotic shrimp in a reef tank. It focused on one species (which isn't my personal fav.) but also made a point in mentioning that it was very similar for the othr species. It strongly recommended them for smaller tanks, because once they get used to the tank they are out alot and they never stray too far from their whole. I had once species a while ago (Stonogobiops nematodes) in a 5g and it did wonderfully. I don't have the shrimp though so I constucted a "cave dwelling" for it with a small 1/4" piece of hard tubing from my LFS, just corked off one end with a rubber cork. He liked it thought I would highly recommend the ship instead. The best shrimp (from what I understand) is Alpheus randalli but A. bellui is also a good option. HTH