We recently added a Diamond Sand Sifting Goby (Diamond) to our 125 gallon mixed reef tank. We had a Wide-Barred Shrimp Goby (Clyde) that was previously paired with a Pistol Shrimp who has not left the corner that they occupied when the Pistol Shrimp was alive despite 2 major changes in the rock structuring in the tank. My LFS warned that the 2 will probably not get along but I figured with the size of the tank and the extensive rock work - we should be ok. I introduced Diamond at the opposite end of the tank from where Clyde resides 3 days ago. To my surprise, yesterday I discovered that Diamond is digging tunnels in Clyde's territory. Today I took a peek into the area to see how they are getting on and was surprised to see both of them sitting side by side in a cave that Diamond had dug. Does Clyde miss his companion shrimp so bad that he accepted Diamond as a substitute? We have 4 wrasses so adding another Pistol Shrimp (or any shrimp for that matter) is out of the question - they just become expensive snacks. Clyde is about 2" longer than Diamond.