the cleaning fish Labroides dimidiatus (Bluestreak cleaner wrasse), as in many cleaner species, client fish seeks to have ectoparasites removed by the cleaners. In these situations, instead of picking off the parasites on the surface of the client fish, the cleaner can cheat by feeding on the client's tissue (mucus layer, scales, etc.), thereby gaining additional benefit from the symbiotic system. It has been well documented that cleaners will feed on mucus when their clients are unable to control the cleaner's behavior; however, in natural settings, client fish often jolt, chase after cheating cleaners, or terminate interactions of swimming way, effectively controlling the cheating behavior. Studies on cleaning mutualisms generally suggest that cheating behavior is often adjusted depending on the species of the client. In cleaning shrimp, cheating is predicted to occur less often because shrimps bear a higher cost if the clients use aggression to control the cleaner's behavior. Studies have found that cleaner species can strategically adjust cheating behavior according to the potential associated risk. For example, predatory clients, which present a significantly high cost for cheating, experience less cheating behavior. On the other hand, nonpredatory clients present a lower cost for cheating, and thus experience more cheating behaviors from the cleaners. Some evidence suggest that physiological processes can mediate the cleaners' decision to switch from cooperating to cheating in mutualistic interactions. For example, in the bluestreak cleaner wrasse, changes in cortisol levels are associated with behavior changes. For smaller clients, increase cortisol levels in the water lead to more cooperative behavior, while for larger clients, the same treatment lead to more dishonest behavior. It has been suggested that "good behavior" toward smaller clients often allow wrasses to attract larger clients that are often cheated. Other Other models of cheating include the European tree frog, "Hyla arborea". In many sexually reproducing species such as this, some males can access mates by exploiting resources of more competitive males. Many species have dynamic reproductive strategies that can change in response to changes in the environment. In these instances, several factors contribute to the decision to switch between mating strategies. For example, in the European tree frog, a sexually competitive (as in, perceived to be attractive by females) male tend to call to attract mates. This is often referred to as the "bourgeois" tactic. On the other hand, a smaller male that would likely fail to attract mates using the bourgeois