234
keeping in view the distribution of the primary
FW fi shes, particularly, those of the order
Cypriniformes.
Megagaea
(i) The Palaearctic: It includes portion of Asia
like Japan, north of the Himalayas and the
Yangtze Kiang watershed, Iran and portion
of Africa, north of Sahara.
(ii) The Nearctic: It includes North America
amongst other portions.
(iii) The Ethiopian region: It includes Africa,
south of Sahara, including Madagascar.
(iv) The Oriental region: It includes India, Sri
Lanka, Thailand, southern China and the
Malayan archipelago.
Neogaea
(v) The Neotropical region: It includes America
from Mexico southwards.
Notogaea
(vi) The Australian region: It includes mainly
Australia, Tasmania, New Zealand and the
Pacifi c islands.
15.5.2.2 Tropical Fish Communities
The tropical Asian ichthyofauna constitutes a
substantive part of the total lotic and lentic fi sh
communities. The Indo-Chinese peninsula supports 930 species of native FW fi shes which
belong to 87 families (Kottelat 1989 ). A number of tropical Asian FW fi shes are shared with
African riverine ecosystems both at the family
as well as at the generic level. Cyprinids, certain siluriform catfi shes, channids, mastacembelids and notopterids are shared between the
two regions. At the generic level, Anabas,
Clarias, Garra, Labeo and Mastacembelus
occur in both African and Asian rivers. Certain
fi shes, like tilapia, which have been introduced
into India from Africa, have become widespread all over southern Asia. They have also
replaced the native population in some places
due to their dominance. There is large-scale
abundance of cyprinids and balitorids in Asia in
contrast to predominance of characids and cichlids in Africa. Incidentally, research on the
ecology of the tropical fi sh communities is limited (Dudgeon 1995 ). Further, there have been
studies on fi sh diets and resource partitioning in
certain Sri Lankan hill streams (Wikramanayake
and Moyle 1989 ). Niche’ segregation is dependent
on seasonality, diet and habitat utilisation as
was revealed from their studies. Also, there are
morphological segregation and specialisation
in these fi sh communities.
15.5.2.3 Ichthyogeography of India
In order to explain the occurrence and assemblage of FW fi sh fauna of India in relation to contiguous lands, various views have been put
forward. A close affi nity between the fi sh fauna
of Indian and African regions had been noted by
Gunther ( 1880 ), who had pointed out that one or
more representatives of the 17 out of 26 families
or groups found in India also exist in Africa.
Further, many African species are not generically
different from those of India. Gunther had
included Asia, south of the Himalayas and the
Yangtze Kiang and the islands to the west of
Wallace line under the Indian region. Day ( 1885 )
had differed from Gunther and had recorded 87
genera of FW fi shes in India (including Burma
and Ceylon within it). Out of these, only 14 were
represented in Africa. He further had observed
that out of the 369 species belonging to these
genera, the distribution of only 14 was known to
extend to Africa. Day had been supported by
Blanford ( 1901 ) who had studied the occurrence
and distribution of the vertebrates, in general.
Blanford had concluded that the elements in
Indo-Malayan fauna are generally heavily represented in the Eastern Himalayas, which diminishes gradually westwards and tends to cease in
Kashmir and further west. Hora ( 1937 ) had also
supported this view and advocated a southeastern
Asian origin of the FW fi sh fauna of India emanating, most probably, from the Yunnan Province
of China. Further, according to him, this ichthyofauna had spread westwards in successive waves
of migration, fi rst to India and later to Africa, at a
time, when the two land masses were said to have
been connected. Still further, Hora ( 1937 ) had
critically studied 41 Indian fish genera and
had concluded that the Indian fi sh fauna not only
had marked Malayan affi nity but were also
related to the fauna of Thailand, southern China
and Cochinchina. Menon ( 1955 ) had supported
15 Wetland Flora, Plankton, Productivity, Fauna and Fishes
keeping in view the distribution of the primary
FW fi shes, particularly, those of the order
Cypriniformes.
Megagaea
(i) The Palaearctic: It includes portion of Asia
like Japan, north of the Himalayas and the
Yangtze Kiang watershed, Iran and portion
of Africa, north of Sahara.
(ii) The Nearctic: It includes North America
amongst other portions.
(iii) The Ethiopian region: It includes Africa,
south of Sahara, including Madagascar.
(iv) The Oriental region: It includes India, Sri
Lanka, Thailand, southern China and the
Malayan archipelago.
Neogaea
(v) The Neotropical region: It includes America
from Mexico southwards.
Notogaea
(vi) The Australian region: It includes mainly
Australia, Tasmania, New Zealand and the
Pacifi c islands.
15.5.2.2 Tropical Fish Communities
The tropical Asian ichthyofauna constitutes a
substantive part of the total lotic and lentic fi sh
communities. The Indo-Chinese peninsula supports 930 species of native FW fi shes which
belong to 87 families (Kottelat 1989 ). A number of tropical Asian FW fi shes are shared with
African riverine ecosystems both at the family
as well as at the generic level. Cyprinids, certain siluriform catfi shes, channids, mastacembelids and notopterids are shared between the
two regions. At the generic level, Anabas,
Clarias, Garra, Labeo and Mastacembelus
occur in both African and Asian rivers. Certain
fi shes, like tilapia, which have been introduced
into India from Africa, have become widespread all over southern Asia. They have also
replaced the native population in some places
due to their dominance. There is large-scale
abundance of cyprinids and balitorids in Asia in
contrast to predominance of characids and cichlids in Africa. Incidentally, research on the
ecology of the tropical fi sh communities is limited (Dudgeon 1995 ). Further, there have been
studies on fi sh diets and resource partitioning in
certain Sri Lankan hill streams (Wikramanayake
and Moyle 1989 ). Niche’ segregation is dependent
on seasonality, diet and habitat utilisation as
was revealed from their studies. Also, there are
morphological segregation and specialisation
in these fi sh communities.
15.5.2.3 Ichthyogeography of India
In order to explain the occurrence and assemblage of FW fi sh fauna of India in relation to contiguous lands, various views have been put
forward. A close affi nity between the fi sh fauna
of Indian and African regions had been noted by
Gunther ( 1880 ), who had pointed out that one or
more representatives of the 17 out of 26 families
or groups found in India also exist in Africa.
Further, many African species are not generically
different from those of India. Gunther had
included Asia, south of the Himalayas and the
Yangtze Kiang and the islands to the west of
Wallace line under the Indian region. Day ( 1885 )
had differed from Gunther and had recorded 87
genera of FW fi shes in India (including Burma
and Ceylon within it). Out of these, only 14 were
represented in Africa. He further had observed
that out of the 369 species belonging to these
genera, the distribution of only 14 was known to
extend to Africa. Day had been supported by
Blanford ( 1901 ) who had studied the occurrence
and distribution of the vertebrates, in general.
Blanford had concluded that the elements in
Indo-Malayan fauna are generally heavily represented in the Eastern Himalayas, which diminishes gradually westwards and tends to cease in
Kashmir and further west. Hora ( 1937 ) had also
supported this view and advocated a southeastern
Asian origin of the FW fi sh fauna of India emanating, most probably, from the Yunnan Province
of China. Further, according to him, this ichthyofauna had spread westwards in successive waves
of migration, fi rst to India and later to Africa, at a
time, when the two land masses were said to have
been connected. Still further, Hora ( 1937 ) had
critically studied 41 Indian fish genera and
had concluded that the Indian fi sh fauna not only
had marked Malayan affi nity but were also
related to the fauna of Thailand, southern China
and Cochinchina. Menon ( 1955 ) had supported
15 Wetland Flora, Plankton, Productivity, Fauna and Fishes