96
the large stream zones are frequented by
Schizothorax longipinnis , S. planifrons and S.
micropogon . The least rapid reaches of this zone
are occupied by Garra gotyla , Crossocheilus
diplochilus , Labeo dero and L. dyocheilus ; (iii)
slow moving meandering zone is inhabited by
a large number of cold to eurythermic species
such as Barilius spp., Tor spp. catfi shes,
homalopterid fi sh ( Homaloptera spp.) and
snakeheads ( Channa spp.).
Earlier, Menon (1954) had related the distribution pattern of Himalayan fi sh to morphological characteristics which enable them to inhabit
the torrential streams. He recognised six major
groups: (a) fi shes dwelling in shallow, clear cold
waters in the foothills without any striking
modifi cations to current, Labeo , Tor , Barilius
and Puntius ; (b) fi sh inhabiting the bottom water
layers in deep fast current, with powerful muscular cylindrical bodies, schizothoracines and the
introduced trouts; (c) fi sh sheltering amongst
pebbles and stones to ward off the strong current,
Crossocheilus diplochilus ; (d) fi sh sheltering
amongst pebbles and shingles in shallows, with
special attachment devices, the loaches
Nemacheilus , Botia and Amblyceps ; (e) fi sh
which cling to exposed surfaces of bare rocks in
slower current, with adhesive organs on their
ventral surface for attachment to rocks, Garra ,
Glyptothorax and Glyptosternon ; and (f) fi sh
which cling to the exposed surfaces of bare rocks
in fast current, with limpet-shaped bodies and
mouth, gills and fi ns highly modifi ed to suit the
habitat, Balitora .
Further, Hora (1955) and Menon (1962)
studied the evolution of schizothoracines and
concluded that they appeared during the fi rst
interglacial period. Primitive forms of this
group occur even today in South China. During
the favourable environmental conditions of the
second glacial period, they had migrated westwards as far as Kashmir and Sistan. The great
proliferation of Schizothoracines had, probably, occurred during the second and subsequent
interglacial periods. Today, the schizothoracines are mainly Central Asian in distribution,
although a few species are present also along
the southern face of the Himalayas. This is,
perhaps, on account of the Trans-Himalayan
origin of some of the major rivers like the
Indus, the Ganges and the Brahmaputra, which
made it possible to descend to the lower reaches
of these rivers.
Concomitantly, the eastern Himalayas,
drained by the Brahmaputra, has a greater diversity of cold-water fi sh than the western Himalayan
drainage. For the whole Himalayas, 218 species
had been listed (Menon 1962). The subsistence
and commercial fi sheries generally exploit the
carps ( Labeo and Tor spp.), lesser barils
( Barilius spp.), schizothoracines ( Schizothorax
and Schizothoraichthys spp.), garrids ( Garra spp.)
and sisorids ( Glyptothorax and Glyptosternon
spp.). The other genera are small sized and of low
economic value. However, the exotic brown trout
( Salmo trutta ) is said to have established itself in
some areas of the Himalayas.
Notwithstanding the above, the main factors
which infl uence fi sh life in the Himalayan streams
are (i) current velocity, (ii) fl uctuation in water
discharge, (iii) water temperature and dissolved
oxygen level, (iv) substratum, (v) shelter from the
current and (vi) food availability represented
mostly by organisms clinging to and growing on
rock and stone surfaces in fast current.
Of all these factors, water temperature is
always an important limiting factor affecting
geographical distribution and local occurrence
within one water system. Cold stenothermic
species such as the endemic schizothoracines
( Schizothoraichthys esocinus and Diptychus
maculatus ) and exotic brown trout have an
upper tolerance around 20 °C. Carps, mahseers
and lesser barils usually have a wider tolerance
and even survive water temperatures >25 °C.
However, the schizothoracines and brown trout
remain active in the near-zero temperature
which prevail in streams of the Lesser and
Greater Himalaya during December and
January. Schizothoracines, the indigenous cyprinids (also called snow trout) are well adapted
to such conditions. They are fi shes of streams
and lakes and are fi shed by subsistence, fulland part-time fi shermen.
Nevertheless, the schizothoracines migrate
from headwaters to lower altitudes (in order to
6 Lakes of the World
the large stream zones are frequented by
Schizothorax longipinnis , S. planifrons and S.
micropogon . The least rapid reaches of this zone
are occupied by Garra gotyla , Crossocheilus
diplochilus , Labeo dero and L. dyocheilus ; (iii)
slow moving meandering zone is inhabited by
a large number of cold to eurythermic species
such as Barilius spp., Tor spp. catfi shes,
homalopterid fi sh ( Homaloptera spp.) and
snakeheads ( Channa spp.).
Earlier, Menon (1954) had related the distribution pattern of Himalayan fi sh to morphological characteristics which enable them to inhabit
the torrential streams. He recognised six major
groups: (a) fi shes dwelling in shallow, clear cold
waters in the foothills without any striking
modifi cations to current, Labeo , Tor , Barilius
and Puntius ; (b) fi sh inhabiting the bottom water
layers in deep fast current, with powerful muscular cylindrical bodies, schizothoracines and the
introduced trouts; (c) fi sh sheltering amongst
pebbles and stones to ward off the strong current,
Crossocheilus diplochilus ; (d) fi sh sheltering
amongst pebbles and shingles in shallows, with
special attachment devices, the loaches
Nemacheilus , Botia and Amblyceps ; (e) fi sh
which cling to exposed surfaces of bare rocks in
slower current, with adhesive organs on their
ventral surface for attachment to rocks, Garra ,
Glyptothorax and Glyptosternon ; and (f) fi sh
which cling to the exposed surfaces of bare rocks
in fast current, with limpet-shaped bodies and
mouth, gills and fi ns highly modifi ed to suit the
habitat, Balitora .
Further, Hora (1955) and Menon (1962)
studied the evolution of schizothoracines and
concluded that they appeared during the fi rst
interglacial period. Primitive forms of this
group occur even today in South China. During
the favourable environmental conditions of the
second glacial period, they had migrated westwards as far as Kashmir and Sistan. The great
proliferation of Schizothoracines had, probably, occurred during the second and subsequent
interglacial periods. Today, the schizothoracines are mainly Central Asian in distribution,
although a few species are present also along
the southern face of the Himalayas. This is,
perhaps, on account of the Trans-Himalayan
origin of some of the major rivers like the
Indus, the Ganges and the Brahmaputra, which
made it possible to descend to the lower reaches
of these rivers.
Concomitantly, the eastern Himalayas,
drained by the Brahmaputra, has a greater diversity of cold-water fi sh than the western Himalayan
drainage. For the whole Himalayas, 218 species
had been listed (Menon 1962). The subsistence
and commercial fi sheries generally exploit the
carps ( Labeo and Tor spp.), lesser barils
( Barilius spp.), schizothoracines ( Schizothorax
and Schizothoraichthys spp.), garrids ( Garra spp.)
and sisorids ( Glyptothorax and Glyptosternon
spp.). The other genera are small sized and of low
economic value. However, the exotic brown trout
( Salmo trutta ) is said to have established itself in
some areas of the Himalayas.
Notwithstanding the above, the main factors
which infl uence fi sh life in the Himalayan streams
are (i) current velocity, (ii) fl uctuation in water
discharge, (iii) water temperature and dissolved
oxygen level, (iv) substratum, (v) shelter from the
current and (vi) food availability represented
mostly by organisms clinging to and growing on
rock and stone surfaces in fast current.
Of all these factors, water temperature is
always an important limiting factor affecting
geographical distribution and local occurrence
within one water system. Cold stenothermic
species such as the endemic schizothoracines
( Schizothoraichthys esocinus and Diptychus
maculatus ) and exotic brown trout have an
upper tolerance around 20 °C. Carps, mahseers
and lesser barils usually have a wider tolerance
and even survive water temperatures >25 °C.
However, the schizothoracines and brown trout
remain active in the near-zero temperature
which prevail in streams of the Lesser and
Greater Himalaya during December and
January. Schizothoracines, the indigenous cyprinids (also called snow trout) are well adapted
to such conditions. They are fi shes of streams
and lakes and are fi shed by subsistence, fulland part-time fi shermen.
Nevertheless, the schizothoracines migrate
from headwaters to lower altitudes (in order to
6 Lakes of the World