Signals transmit information to receivers about sender attributes, increase the fitness of both parties, and are selected for in cooperative interactions between species to reduce conflict [1, 2]. Marine cleaning interactions are known for stereotyped behaviors [3-6] that likely serve as signals. For example, "dancing" and "tactile dancing" in cleaner fish may serve to advertise cleaning services to client fish  and manipulate client behavior , respectively. Cleaner shrimp clean fish , yet are cryptic in comparison to cleaner fish. Signals, therefore, are likely essential for cleaner shrimp to attract clients. Here, we show that the yellow-beaked cleaner shrimp  Urocaridella sp. c  uses a stereotypical side-to-side movement, or "rocking dance," while approaching potential client fish in the water column. This dance was followed by a cleaning interaction with the client 100% of the time. Hungry cleaner shrimp, which are more willing to clean than satiated ones , spent more time rocking and in closer proximity to clients Cephalopholis cyanostigma than satiated ones, and when given a choice, clients preferred hungry, rocking shrimp. The rocking dance therefore influenced client behavior and, thus, appears to function as a signal to advertise the presence of cleaner shrimp to potential clients.