Seems like I read something recently about certain types of cleaner shrimp...I think it was a pistol shrimp...and Goby's will pair like that. They actually develop a symbiotic relationship. They live together in the same place & both are collectors. The article talked about how the shrimp would steadfastly stay by his goby friends side making sure to keep the goby well groomed...mouth and all!

I noticed our Blood Shrimp hanging out with Engineer Goby. I didn't realize it until I was feeding some brine shrimp to "Winston", and sitting there with him eating, was the blood shrimp. The blood shrimp is relatively new to the tank and has kept himself hidden well. Now he comes for dinner with Winston all the time. I wonder if Winston is getting cleaned by the blood shrimp. Ill have to watch and see. It's pretty neat.