Europe, except the carp, are met with in the lakes and rivers in immense quantities, the characteristic feature of the region being its wealth in Coregoni and in Salmonidae generally.
The Salmonidae are entirely absent from the waters of southern Asia, though they exist in the rivers that flow into the Arctic Ocean and the neighbouring parts of the northern Pacific, extending perhaps to Formosa; and trout, though unknown in Indian rivers, are found beyond the watershed of the Indus, in the streams flowing into the Caspian.
The waters of the lake swarm with fish (sturgeons and salmonidae), and its herring (Salmo omul) is the chief product of the fisheries, though notably fewer have been taken within the last forty or fifty years.
Mackerel, cod, pollack and flat-fishes are the kinds most frequently attacked by them in the sea; of river-fish the migratory Salmonidae and the shad are sometimes found with the marks of the teeth of the lamprey, or with the fish actually attached to them.
The most important case of naturalization of fish is, however, the establishment of some Salmonidae in Tasmania and New Zealand.