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The
Labyrinth Fishes
The Labyrinth
fishes, also known as anabantoids (with the families Anabantidae,
Belontiidae, Osphronemidae,
Helostomatidae, Luciocephalidae), vary in appearance;
some elongated and torpedo-shaped, others flat and deep-bodied. Some
gouramies, e.g., Osphronemus and Trichogaster, possess stiff, thread-like
pelvic fins which are said to act as organs of touch.
They are well equipped to utilise atmospheric air by possessing a
special accessory respiratory organ situated just above the gills,
in a large extension on the upper part of the gill-chamber. It is
composed of lamellae, covered with an extremely vascular layer of
skin, and convoluted into numerous folds to maximise the surface area
for air absorption. Because the structure resembles a complicated
maze, it has been dubbed the labyrinth organ. |
The
variety of
body shape of labyrinth fishes
Luciocephalidae
Helostomatidae
Belontiidae
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Labyrinth organ of Anabas |
The
anabantoid breathes by gulping air periodically from the water surface,
which is then channelled into the labyrinth organ for gaseous exchange.
This facility is not present in the anabantoid fry, only developing
some weeks after hatching. All known anabantoids will drown if deprived
of access to water surface.
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Many anabantoids are
bubble-nest breeders (especially the family Belontiidae and Osphronemidae).
The males usually construct a floating nest of bits and pieces of vegetation,
held together with scores of bubbles blown by the male with the help of
a mucous secretion from the mouth. The nest serves to keep the eggs together,
so they are easier to guard, and it also serves to keep the young fry, which
have not yet developed the labyrinth organ, near the well oxygenated water
surface. |
Introduction
Freshwater habitats
Fishes in Singapore
Conservation
Amazing Fishy Facts
About the guidebook |
