I haven't had a Yasha, but I have gone through the wars of trying to get a shrimp goby to pair up with a pistol shrimp. As a matter of fact, I have 3 different pistol shrimp in my tank right now. First, I purchased my yellow watchman goby (I have had him 6 months or so now). I couldn't find a pistol, of any variety, at the time. About a month later, I purchased a Caribbean pistol shrimp. The pistol shrimp immediately went and hid among my rocks and never dug any sand. The goby would go close to him, but they just didn't have any interest in each other. Another month, or so, passed and I found a Bullseye Pistol at another LFS. He was digging in the LFS's aquarium, so I thought I had found my mate for my goby. WRONG! The Pistol dug him a hole, in the front of my tank, under a small piece of coral. The goby came over and rested just outside the hole, then SNAP, POP... the pistol shrimp ran him off. They have never really paid each other any attention since. About 3 weeks ago, I found a Tiger Pistol in yet another LFS. I purchased him and brought him home, acclimated him and introduced him into the tank. Within 2 hours, my goby and the Tiger were buddies. You never can tell. It's really a hit and miss situation, though, from everything I have heard, the Tiger Pistol is the easiest one to pair up with.