field guide to the freshwater fishes of singapore

Index of fishes
General parts of a fish
Kelvin K P Lim and Peter K L Ng
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




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.
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.
Freshwater habitats
Fishes in Singapore
Amazing Fishy Facts
About the guidebook
From A Guide to Common Freshwater Fishes of Singapore by Kelvin K P Lim and Peter K L Ng
Published by the Singapore Science Centre and sponsored by BP

@Raffles Museum of Biodiversity Research and Singapore Science Centre