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

Very often, we hear of people campaigning to conserve birds and mammals - colourful and attractive creatures which easily prick the conscience of the layman and "nature lovers".

Hardly any emphasis, however, is ever bestowed on the lower vertebrates, e.g., reptiles, amphibians, fish, and most invertebrates, with the glaring, biased exception of corals and butterflies! While these "creepy-crawlies" or "slimy things" may not be visually so pleasant to the majority of human perceptions, they are equally, if not more vulnerable.

We take fishes for granted, probably also because we see them in aquaria so often. Some of our primary freshwater fishes however, are probably amongst the most threatened of Singapore's wildlife. Even today, it is not surprising to find students exclaiming that guppies, mollies and tilapias are part of Singapore's "natural heritage". Who can blame them? What other kinds do they really see or hear about which are truly "Singaporean"?

What causes many of the indigenous fishes to be labelled as endangered or rare? The reasons are many, of which the main cause is development.

Singapore island has indeed changed a great deal in the past century. Large areas of forest have been destroyed to make way for factories and housing estates; many forest streams and other natural water channels have been lined with concrete, soiled with pollutants or buried under the construction of catchment reservoirs. As such the home range for certain native fishes shrank considerably, with only small populations still hanging on in the few lesser disturbed streams of the Central Catchment forest.

In 1934, two well known ichthyologists reported 52 indigenous primary freshwater fishes from Singapore. Only about 29 survive today, an almost 30% loss! Of these 29 species, 18 are endangered. This means that 62% of our native primary freshwater fish fauna is threatened with extinction.
The following fishes have all almost certainly vanished, unable to adapt to the changing conditions of an urbanised Singapore. Fortunately, they are still present in Malaysia. Every effort must now be made to ensure that the remaining natural fish fauna does not go the same way!

Clown Barb
Puntius dunckeri

Tinfoil Barb
Barbodes schwanenfeldii

Labiobarbus festivus
Photo: Esther Koh

Hampala macrolepidota
Photo: Esther Koh

Head-band Rasbora
Rasbora cephalotaenia

Banded Leaf Fish
Pristolepis fasciata
Another major problem is that of commercial fish collectors for the aquarium trade. Commercially important species like the Harlequin Rasbora, Pygmy Rasbora, Six-Banded Tiger Barb and Banded Eel-loach, to name a few, have been so heavily depleted that they are now very difficult to see in the wild.

Casual collection of fish for any purpose whatsoever within the stated nature reserve boundaries is illegal and should not be practised without a permit issued by the Public Utilities Board or Nature Reserves Board.

A possibly troublesome problem is the introduction of foreign animals into our waterways.

It is significant to note that in urban Singapore, most of the common fishes seen are introduced ones. Tilapia, guppies and mollies abound. All are "immigrants" which have adapted well to a concretised environment. Fortunately, these fishes are scarce in the catchment areas.

The number of established exotic species has increased from about seven species in 1934 to at least 14 at the time of writing. Foreign animals, once established, can have detrimental effects on the indigenous flora and fauna in that they may out-compete some native species, or introduce diseases which may prove fatal to them.

The ornamental fish trade has played a major role in the establishment of several alien species, e.g., the Mollies, Flying Barb, Red-tailed Rasbora and Armoured Sucker Catfish.

Aquaculture has introduced cyprinids like the Chinese Barb and Striped Chinese Minnow.

The introduction of various livebearers to combat mosquitoes (e.g., Guppies and Mosquito Fishes) can also be a potential threat to the local fauna.
Many fishes, however, will probably become established in Singapore in the years to come. They will then join the ranks of the numerous "immigrants", several of which are already Singapore's most common fishes.

Moonlight Gouramy
Trichogaster microlepis
Photo: Tan Bee Hong

Dwarf Gouramy
Colisa lalia

Xiphophorus maculatus

Oscar Cichlid
Astronotus ocellatus
Photo: Tan Bee Hong

Colossoma sp.

Silver Catfish
Pangasianodon sutchi
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