How anemonefish acquire immunity from stinging tentacles remains uncertain, however, it is generally agreed that the fish��s mucus plays an important role in its protection either through a blocking mechanism or through inhibition by mimicry. Twenty-six species of anemonefish in the genus Amphiprion and monospecific Premnas, are found in only 10 species of anemones which act as hosts. Patterns of host Rituximab anemone usage indicate that some anemone species are preferred by anemonefish as they will compete for them, and they have large numbers of fish species associated with them, whereas other anemones have only a single anemonefish species in association and will only be used if no other anemone is available. Hypotheses BRD32048 explaining the different patterns of relationship between anemonefish species and anemone species have been proposed by Fautin and Murata et al., and include, olfaction, innate preference, competitive exclusion, and environmental requirements of the symbionts. Anemone use by different anemonefish species cannot be fully explained by innate or conditioned preference hypothesis,,, as some anemonefish are known to move from one anemone species as juvenile to a different anemone species as adults. The claim that different anemone species must provide different fitness levels to fish however has been made, but what particular anemone attributes contribute to fish fitness has yet to be determined. Understanding the relationship between fish and anemone hosts and in some cases the extreme forms of specialization and generalisation by anemonefish has resulted in studies using multifaceted approaches such as phylogenetic analysis and mathematical models to decipher the complex pattern exhibited by this family of fish. These hypotheses have primarily focused on the relationship from the perspective of the fish whereas the influence of the anemone on this association has received less attention and may be key to understanding important aspects of the symbiosis. This rather complex symbiotic relationship requires an understanding of the requirements of both host and symbiont in order to understand the establishment and maintenance of the relationship.