A catalogue of described genera and species of microsporidians parasitic in fish.

A complete list of microsporidians parasitic in fish is presented; in each species, the host(s), site of infection and the known geographical distribution is given. Species of a total of 14 genera can be found in fish hosts. These genera do not occur in other hosts and include 80 named species plus 29 records only designated as 'sp.' The collective group Microsporidium includes 15 species plus 30 records only designated as 'sp.' Described species with incorrect generic assignment number seven species and there are six hyperparasitic species infecting other fish parasites. Thus the total number of microsporidians which may be encountered in fish is 108 named and 59 innominate species.