Ray1214,
I have a pair. A
Tiger Pistol Shrimp and a Randall's Goby. My kids gave me the pair a year ago at Christmas. My first shrimp lived for a bout a year before he disappeared. Very sad, although I'm learning that he was probably quite old when I got him. He was over 3" long when he died. We bought the shrimp and goby separately and it took all of about 30 seconds for them to find each other and pair the first time. THey stayed togher for the year. My goby just wasn't the same without the shrimp.
I bought another pistol, to replace the first. It is a reddish color with blue legs and edges on its tail. The goby won't look at it.
A month later, I found another
Tiger Pistol shrimp in the LFS. Bought it, and the goby paired with it about 10 seconds after it hit the water! The two are never more than a couple inches apart, and haven't been for going on 3 months now.
Also, the two pistols, seem to have staked out different territories, and are never seen to encroach on each other
Here is the lesson. The Tiger Pistol is an indo-pacific species, as are the watchman-type gobies. There are pistols from the Caribbean, which my second one was. I've been told now that the Caribbean does not have any watchman-type gobies, so the two don't know about pairing. An Indo-pacific goby and an indo-pacific pistol will almost always pair. And that is true in my experience.
Also, I'd think you may want to go a little larger than a 5 gal tank for a pair. A 10 would probably be OK, a 15 would be great. They don't need a lot of surface space, but my Tiger Pistol must have a huge underground network. He has several doorways, and moves a LOT of sand. (I have them in a 55 now.) Make sure you include a good solid foundation for any LR in the tank, or the shrimp WILL undermine it and cause it to fall!
My suggestion would be to do some research on the watchmans, pick one you like (like the Randall's, which is my favorite), and then get a Tiger Pistol to go with it. Don't bother paying the extra price for a "Pair." If you get a Tiger Pistol, they will probably pair-up on their own.
HTH
Sally - The clown gobies are not of the watchman-type, and I don't think they will pair with a shrimp.
Daryl