The Red Sea is generally considered zoo geographically as an appendix of the Indian Ocean. In reality this sea has its own paleogeographic history, beginning as a bay of the Mediterranean Tethys in early Tertiary and isolated for a rather, long time during the Pleistocene.

The ichthyofauna, especially the coastal fishes there can be distinguished as three different groups of immigrants to the Red Sea. Thus the Red Sea fauna is different in many aspects from the fishes of the Indian Ocean and has numerous endemic species. The ichthyofauna of the East African coast is influenced by the fishes of the Red Sea.

The Indian Ocean is not a homogeneous unit with a uniform ichthyofauna. The eastern part till India and the Maldives is different from the western part. As the Indo-Australian Archipelago shows also different conditions the whole Indian Ocean region has to be divided into four subregions, including the Red Sea in the west and the Indo-Australian Archipelago in the east.