[Delphinus]

They will be OK singly, but I do recommend getting more, their behaviour will be MUCH more interesting to observe as a group instead of just a single individual. The more there are, the more bold they will be. IMHO: Two shrimp are better than one, and 3 or more are better than 2.

Having had (at one time, completely by accident), ordering more than I had intended, thinking I was going to put 2 pairs into 2 different tanks, I somehow ended up with 5. I decided, what the heck, I'm putting them all into one tank. The group dynamics were astounding, they're far more clever than we give them credit for. One example - you could tell one was about to molt by observing the others; they totally knew. I also learned that mating must occur shortly after a molt because man they go beserk on the molting shrimp afterwards (and then suddently the next day one of them would be carrying eggs -- hmmmmmmm). You'll also see cleaning stations get set up if you have a group (you might observe it with a single individual but it's more apparent with a group, IMO).

I've found this to be true for both the scarlet cleaners and peppermints (both Lysmata genus). So I presume this would also hold true for fire shrimp but I would not know about other species of shrimp. The Lysmata sp. shrimp appear to be rather social animals; unusual (IMO), for crustaceans.