The known fish fauna of the Maldives now stands at some 1100 species. This is double the number
of species that was known from the Maldives prior to the formation of the Marine Research Section
in 1984. This leap in knowledge reflects the great amount of work carried out by the Centre, some
of it in collaboration with the World’s foremost authority on tropical reef fishes, Dr John E. Randall
of the Bishop Museum, Hawaii. There are undoubtedly many more species to be found in Maldivian
waters, and the grand total is likely to exceed 1500 species.
Despite the rich fish fauna, Maldives has very few endemic species (i.e. ones that are found here
and nowhere else). Even the so-called Maldive Anemonefish, Amphiprion nigripes is found in the
Lakshadweep and Sri Lanka in addition to Maldives. One species listed here that is so far known
only from the Maldives is the tiny Maldive Blenny, Ecsenius minutus.
It may seem strange that so few endemic fishes are found in Maldives, when some species appear
to move no more than few meters or even centimetres throughout there adult lives. The answer to
this riddle is to be found in the larval stage. All reef fishes have what has been called a two-phase
life history; adult and larva. While reef fishes maybe bound to the coral homes, the larvae are
planktonic and drift with the currents.
The larvae of most species drift in the open ocean for at least one week, and in some cases for
several months. During this time, they can be carried for hundreds, if not thousands of miles by the
ocean currents. As a result, the majority of Maldivian reef fishes (probably about 80 per cent) have
very wide distributions that cover the entire Indo-west Pacific or Indo-Pacific realm.
The Indian and Pacific Ocean are connected in tropical latitudes through the Indonesian Archipelago
and around the north of Australia. Therefore, the larvae of reef fishes from the two Oceans can mix.
In contrast, the tropical Atlantic Ocean is isolated from the warm waters of both the Indian and
Pacific by wide expanses of cold waters. Thus, the tropical fish fauna of the Indian Ocean and
Pacific Ocean are very similar, while that of the Atlantic is very distinct.