Adding another Randall's goby

[Grouperhead]

I currently have one Randall's goby in my 20g. He's been in there since last Tuesday, and is currently the only fish in the tank. I'd like to add another Randall's in hopes of them pairing up, but before I do I'd like to make sure I won't be creating a problem with a new addition. Any thoughts on the matter? I know some shrimp gobies can be territorial, but I haven't read anything regarding this in Randall's. The current goby is around 1.25-1.5" and there are two tiger pistol shrimp around .75-1" which it has already paired up with.

Thoughts?

 

[Fish Biscuit]

I don't know if there's a way to determine the sex of a Randall. You might be better off getting something else, you could fit 2 or 3 more small fish in there. Maybe a blenny and a royal gamma, or check out the nano section on Live Aquaria for other ideas.

 

[KChan]

If you get one from a LFS, you could probably return it if they are not compatible.