removed when colonies are satiated, there is a significant drop in weight of the active workers because the lazier workers are taking advantage of the system. Punishment is also a method used by cichlid Neolamprologous pulcher in their cooperative breeding systems. It is a pay-to-stay system where helper fish are allowed to stay in certain territories in exchange for their help. Similar to the naked mole rats, the helpers that were prevented from helping, the "idle helpers", receive more aggression than control helpers in the study. Researchers theorize that this system developed because the fish are usually not closely related (so kinship benefits have little impact), and because there is a high level of predation risk when the fish is outside the group (therefore a strong motivator for the helper fish to stay in the group). Rhesus monkeys also use aggression as a punishment. These animals have five distinct calls that they can "decide" to produce upon finding food. Whether they call or not is related to their sex and number of kin: females call more often and females with more kin call more often. However, sometimes when food is found, the individual ("discoverer") does not call to attract its kin and, presumably, to share food. If lower ranked individuals find this discoverer to be in the food drop area of the experiment, they recruit coalition support against this individual by screaming. The formed coalition then chases this individual away. If higher ranked individuals find this discoverer, they either chase the discoverer away or became physically aggressive towards the individual. These results show that aggression as punishment is a way to encourage members to work together and share food when it is found. Interspecific countermeasures Cheating and constraints of cheating are not limited to intraspecific interactions; it can also occur in a mutualistic relationship between two species. A common example is the mutualistic relationship between cleaner fish Labroides dimidiatus'' and reef fish. Bshary and Grutter found that cleaner wrasse prefers the client tissue mucus over ectoparasites. This creates a conflict between the cleaner fish and reef fish, because the reef fish only benefit when the cleaner fish eats the ectoparasites. Further studies revealed that in a lab setting, the cleaner fish undergoes behavioral change in face of deterrents against eating their preferential food. In several trials, the plate of their preferential food source was immediately removed when they eat it,