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Official
Magazine of the Nature Society (Singapore)
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They are the commonest representatives from the cyprinid or carp family in our forests. The Elegant Rasbora is also the largest species of native rasbora here. Closely related to the Two Spot Barb, the Spanner Barb (Puntius lateristriga) is rather rare here. This species is more of a midwater feeder than the Two Spot which spends a lot of time probing the substrate with its sensitive barbels. Four other species of cyprinids that inhabit streams are the Chemperas (Cyclocheilicthys apogon), Bankan Rasbora (Rasbora bankanensis), Einthoven's Rasbora (Rasbora einthovenii) and the famous Harlequin Rasbora (Rasbora heteromorpha). The last can be found in quite large shoals. Highly popular among aquarists, the Harlequin Rasbora, with its hues of pink, red and silver is perhaps one of the most beautiful native fishes. This interesting fish lays its eggs on the undersides of Cryptocoryne plants. It was actually first discovered in Singapore by an ichthyologist named Duncker in the Botanic Gardens lake. Not so popular but equally beautiful is the orange-coloured Einthoven's Rasbora. Easily identified and separated from similar Rasboras by its lateral stripe that stretches from the head to caudal fins, this hardy fish is the most wide-ranging Rasbora in Singapore, being the only one to be found on our offshore islands. Occasionally, one may see a fish with six bands on it which bears some similarity to the Sumatran Tiger Barb. This fish is the aptly named Six-banded Tiger Barb (Puntius johorensis), a fish that has a confusing taxonomy. Nevertheless, it is highly prized by collectors and any further collecting will definitely push the species right to the brink of extinction. Some forest fishes are very difficult to observe in the wild. These are loaches, mostly shy and secretive fishes save for the Grey-banded Loach (Nemacheilus selangoricus). All are also locally endangered. The Banded Coolie Loach (Pangio semicincta) and Spotted Loach (Pangio shelfordi) are aquarium favourites, the same reason that has caused it to be rare in the wild. These fishes are benthic feeders, meaning they feed in the bottom substrate of streams. Given their habits of burrowing into sand and rotting vegetation, it is not surprising to miss them altogether. The beautiful Grey-banded Loach is easier to see as it often forages in the open, in groups of three or four. 'Splish, Splash!' - this sound is one of the first indications of the Common Walking Catfish's (Clarias batrachus) presence. It is the largest native catfish present in our forest streams. The walking catfishes are more catlike than the other three catfish species found in the same habitat in that they can walk on land with the help of their pectoral spines and wiggly bodies, just like the Climbing Perch. They are unfortunately unable to mew or purr like a cat. Two species are found here, the Common Walking Catfish and the endangered Forest Walking Catfish (Clarias teijsmanni). The other three catfish species include the very rare Wrinkle-bellied Catfish (Glyptothorax major), the nocturnal Hasselt's Catfish (Silurichthys hasseltii) and the restricted range Little Warty Catfish (Parakysis verrucosus). The last of this trio is now known to be a new species restricted only to streams in Singapore and Southern Johore. Ripples that you see on the surface of streams and ponds will draw your attention to a more bizarre type of fish. Halfbeaks, as they are known, have a much longer lower mandible. To visualise this fish, imagine a scissors with half of one cutting end broken off. Being surface feeders, halfbeaks skim for insects that have fallen onto the stream's surface. Halfbeaks are the only native live-bearing fishes. The species most likely to be spotted are the ubiquitous Pygmy Halfbeak (Dermogenys pusillus), a midget shorter than 5 cm, and the much larger and more colourful Forest Halfbeak (Hemirhamphodon pogonognathus). The terror of fishes, the Pikehead (Luciocephalus pulcher), is like the Pike of European rivers. This is a voracious predator of smaller fishes, especially the diminutive rasboras. A frequent user of 'strategic' ambush tactics, this fish pretends to be a twig (something that it does excellently) and stealthily swims towards its desired meal. When it is close enough, its mouth suddenly throws out a membranous funnel, engulfing the victim and swallowing it whole. Singapore may not have wild elephants, but it certainly has the elephant fish, the alternative commercial name for the spiny eels. This local icthyological curio has a long sensitive probing nose just like the elephant. This feature allows them to feel for bottom- dwelling prey like prawns, larvae and worms. Shy and nocturnal spiny eels conceal themselves in the thick cover of aquatic vegetation during the day, feeding mostly at night. Two species of Spiny Eels (Macrognathus maculatus and Macrognathus perakensis) have been recorded locally, but the latter may have gone the way of the dodo. Any leaf that can swim or move around may actually be a fish. The uncannily shaped Malayan Leaf Fish (Nandus nebulosus) looks more leaf-like than fish-like. This natural wonder hunts just like the Pikehead by employing ambush tactics, except it lacks the protractile mouth. It also takes advantage of its cryptic coloration and odd shape to conceal against its predators, like the snakeheads and piscivorous birds. Our forests offer refuge to some of Singapore's rarest fishes, not forgetting many species of plants, mammals, birds, reptiles and invertebrates. It is a living biological heritage that should deserve more appreciation and recognition than it gets now. In the future, research on the forest may yield even more new and interesting species that might promise cures for some of our diseases. In order for this to happen, the forests and its unique wildlife must be fully protected. Further reading
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© Nature Society Singapore |
The
type of forest where these streams are found is dominated by pandanus,
aroids, pitcher plants and rattan palms. The most visible physical
character of this type of forest is that the vegetation is partially
submerged in acidic water, somewhat like the flooded forest (Igápo)
of the Amazon Basin.
