Seven species of crayfi sh, all in the genus Astacoides Guérin, 1839, are found in Madagascar while the African continent proper lacks a native crayfi sh fauna. Crayfi sh have been known to occur in Madagascar since 1839, in which the fi rst species (A. madagascarensis) was described twice in rapid succession: First as Astacoides goudotii Guérin, 1839 (now suppressed, see Holthuis 1964) and second as Astacus madagascariensis H. Milne Edward and Audouin, 1839. Later authors (Monod and Petit 1929) described four additional taxa as varieties or subspecies of A. madagascariensis, but these are now recognized as valid species (Hobbs 1987). The taxonomy of the crayfi sh of Madagascar was revised by Hobbs (1987) who recognized one genus and six species and gave identifi cation keys for the species; Boyko et al. (2005) subsequently added a seventh species (Table 21.1).