I have a pico 7 gal with a red pistol shrimp and a yasha goby, the shrimp is maybe double the goby size. I'm pretty sure they won't pair, the goby has been in the tank for a month and the shrimp was put in last week. My goby stays at a distance from the shrimp and hides in a rock above or in one tunnel too small for the shrimp to get his hands in. Today my yasha goby had been missing, I put some food in to see if she would come out, I checked the sump since she was in there 2 days ago. Could she be living in the shrimp burrow? I don't really think the shrimp would've killed her but idk