This is a scarlet cleaner shrimp. They are also called northern cleaner shrimp, skunk cleaner shrimp, and Pacific cleaner shrimp. They are called skunk cleaner shrimp because they have a stripe on their back like a skunk.
Scarlet cleaner shrimp clean fish and coral by eating parasites and dead tissue off of the other animals. On a reef in the wild, these shrimp live in groups that act like cleaning stations. When fish have parasites, they will go to these cleaning stations and the shrimp will clean off the fish. The shrimp will even go inside the fish’s mouth and gill cavity, and the fish won’t eat the shrimp because it knows that the shrimp is helping it.
People with saltwater aquariums also like to get these shrimp because the shrimp will clean off the fish and the tank.