I had purchased a yasha paired with a tiger pistol and had him for about two weeks when I went to my favorite LFS last weekend, and what do I see but another yasha goby. This particular fish is absolutely lovely, with really really nice patterning, and good behavior, AND this little fish seems to be getting along with the other yasha goby in the tank, although the LFS tells me they are not a pair. So. . . this puts me in a state of want for this fish. I ask the LFS if I can keep these guys in the same tank, and the LFS tells me, truthfully, that he isn't sure. I look at live aquaria on my phone, which tells me this fish can be kept in groups. So what do I do but buy it. Well, within about 1 hour of going into the tank, the new (larger) yahsa kicks my smaller fish out of his burrow, and steals his tiger pistol buddy. That lasted for about two days. Now my formerly very happy smaller yasha is cowering in a corner of my tank. Not the behavior I wanted to see. So, what do I do but go and buy a second pistol shrimp for the smaller guy to pair with. Thankfully, it has worked, I now have two yashas in two different parts of the tank with 2 pistols. . . but just imagine what two pistol shrimp do to the sand bed in a 20g tank. Needless to say, I've pulled at least 4 frags out of the burrows in the last 48 hours. . . So I ask, why, when all is well in our tanks, do we go ahead and make those impulse buys when we know we really shouldn't?