Pederson Cleaner Shrimp (Anemones Shrimp), Periclimenes pedersoni. They are small shrimp with long wavy antenna that spend most of their time perched on anemones waiting for fish to come by for cleanings. They are often part of big cleaning stations that may involve neon gobies, wrasses, and other cleaner shrimp such as banded coral shrimp and scarlet cleaner shrimp. They seem to prefer the corkscrew anemones and the knobby anemones that live on the offshore hard bottom habitats, but whey will host on just about any Caribbean anemone, including the corallimorphs such as ricordea. They are quite animated in an aquarium and will rock back and forth bouncing their antenna trying to attract the attention of the larger fish so they can check them for parasites.
Although these shrimp do like to nibble the ectoparasites off larger fish in the wild, they do not depend on them for their sole source of food and will easily thrive on almost any kind of food available to them. During feeding times they will actively swim to the surface and take food from your hand, so they are a lot of fun to care for once they get settled into your routine.
These shrimp never get more than about an inch long, so if you have fish such as triggerfish, groupers, wrasses, and snappers, they will probably get eaten so I would not recommend adding them to systems with that type of fish. Sea horses may also eat them, so I would not suggest mixing the two. They are reef safe and would be a great addition to any reef tank, especially a nano tank that has limited space.