I have a tiger pistol shrimp that lost the yellow watchman when I brought them home several months ago. I am wanting to get a new goby for my shrimp. My shrimp is fully grown or very close to being fully grown. What other goby's can I put with the shrimp and what size does it need to be? MY LFS is telling me to stick to yellow watchman and that it needs to be fully grown as the shrimp might kill the smaller yellow watchman.