My son has an 8g biocube and wants a watchman goby and pistol shrimp. that would be the only fish in the tank. Is an 8g big enough? there is a CUC (3 snails and 3 crabs).

Before anyone yells at me...we are not buying these yet. he just wants to start saving his money for fish.

I have a pistol shrimp in my BC8. I think they would probably be fine.

If they are the only two in the tank I think it would be fine and your son will love watching the pistol re-arrange the sandbed and what ever gets in it's way daily.

Yeah, they should be fine.

Any shrimp goby would be fine, but try going with one of the Stonogobiops gobies, like the yasha haze.

thanks guys! Got a new question now. His tank is in his room. Is that pistol shrimp gunna keep him up all night? We had a guy tell us they are noisey.
We should have the pair in a week or two. we actually had to put in an order for them with our LFS. they are hard to find (well petco had them but...)

Shrimp gobies are not going to be scared of a pistol shrimp's snap.

They can be noisey. Mine isn't too bad though. I usually hear it a couple time a night but it's not loud enough to keep me awake at night.