Thursday, April 18, 2013

Freshwater Ray-finned Fishes of Singapore

Ray-finned fishes (phylum Chordata, subphylum Vertebrata, superclass Osteichthyes, class Actinopterygii) are vertebrates (animals with a backbone and a hollow tube of nervous tissue called a spinal cord) characterised by their fins being supported by rays of bony/horny spines, much like those paper folding fan supported by rays of sticks.

Like other members of the superclass Osteichthyes, they have bony skeletons (instead of cartilaginous ones), and have limited physiological means to maintain the body temperature within a narrow range (i.e. they are ectothermic animals). Most species have a layer of scales covering their bodies, while some may have very reduced scales or no scales at all.

Here are some examples of freshwater ray-finned fishes that can be seen in Singapore.


Cypriniform fishes can be recognised by their lack of teeth on their jaws. Instead, they have a pair of gills that are modified into a bone with a series of pharyngeal teeth. Most species only have one dorsal fin.

Family Cyprinidae

Most species from this family have only one soft dorsal fin, and a number of species have short barbels around their mouths.

The Harlequin Rasbora (Trignostigma heteromorpha) is a native freshwater fish that lives in clear, acidic shaded forest streams. This species is gregarious, and can be identified by a black triangular blotch marking the posterior half of the sides of its body. It feeds mainly on small insects and other invertebrates. Being an attractive fish, it is very popular in the aquarium trade. This small fish gets to about 5cm long.

The Einthoven's Rasbora (Rasbora einthovenii) is a native fish that lives mainly in shallow forest streams, though it can sometimes be found in streams in open habitats as well. It is gregarious, and can be identified by a thin, dark lateral line on the sides of its body in the middle, from the tip of its mouth to its tail. It feeds mainly on small invertebrates, growing to about 8cm long.

The Two-spot Rasbora (Rasbora elegans) is a native fish that inhibits forest streams, often in shoals and sometimes with other species. It is usually fast-moving, feeding mostly on small invertebrates. This species can be identified by a dark blotch in the middle of the body, and another smaller one nearer to the tail, though the blotches may be quite faint in some specimens. It grows to about 13cm long.

The Saddle Barb (Systomus banksi) is a native species that is usually found in forest streams, and sometimes in streams in less shady areas. It is gregarious, and can be recognised by a large dark blotch just below the dorsal fin. Sometimes, smaller dark patches can be seen towards the tail. This is an omnivorous species, feeding on water plants as well as small invertebrates. In the earlier days, this fish was sometimes reared in village wells, acting as an indicator that the water was safe for drinking without contamination. It gets to about 10cm long.

The Spanner Barb (Systomus lateristriga) or T-barb is a native species that is usually found in forest streams. It can be identified by having two vertical bands on the anterior half of its body, and a horizontal band on the posterior half. It is omnivorous, feeding on both small invertebrates and plant matter. This is a relatively large barb, growing to about 18cm long.

Family Cobitidae

Members of this family are usually small, elongated, bottom-dwelling fishes with short barbels around the mouth. Their bodies are covered tiny scales. They can be differentiated from similar-looking fishes of the same order by having a spine below the eye.

The Spotted Eel-loach (Pangio muraeniformis), also known as the Spotted Coolie Loach, is a native fish that lives in slow-flowing, shaded forest streams and pools. This eel-like fish is seldom seen, as it usually hides among the leaf litter at the bottom. It can be identified by the long and slender body with irregular dark blotches, the three bands on its head, and three pairs of short barbels around the mouth. This small fish grows to about 8cm long, and feeds on bottom-dwelling invertebrates.


Members of this order are usually eel-like with elongated and slender bodies. However, unlike the true eels, they have poorly developed gills, and many are air-breathing.

Family Mastacembelidae

Members of this family are usually called spiny eels for the series of short spines along their backs. They have rayed fins and a long, proboscis-like snout used for probing in the substrate for small bottom-dwelling invertebrates. They have very tiny scales.

The Buff-backed Spiny Eel (Macrognathus maculatus) is a native species which usually lives in forest streams. It is nocturnal, and hides among the vegetation or under the leaf litter in the day. This is the only spiny eel species known to exist for certain in Singapore, and can be recognised by its dark brown body, light brown back, and proboscis-like snout. It can grow to almost 20cm long, and feeds on small, bottom-dwelling invertebrates.

Family Synbranchidae

Members of this family are commonly called swamp eels. They have long, cylindrical bodies lacking pectoral fins, while the caudal and dorsal fins are very reduced. They are air-breathers, and hence will drown if they cannot get to the water surface. Most species hide in burrows in the day, and only emerge at night to hunt for small animals.

Oriental Swamp Eel (Monopterus albus)
The Oriental Swamp Eel (Monopterus albus) is commonly found in streams, ponds, swamps and even some canals. It has a snake-like appearance, with its dorsal and tail fins being very reduced, and the tail tapers to a point.

Oriental Swamp Eel (Monopterus albus)
The body is brown, often with dark speckles. Oriental Swamp Eels can grow to about 1m long, and are often collected for consumption in the region.


Members of this order are general small and slender fishes. They have teeth in their mouths, and possess prominent scales and a small dorsal fin.

Family Aplocheilidae

Members of this family are usually surface-dwellers and lays eggs. Some species are very colourful.

The Whitespot (Aplocheilus panchax) is a native species which can be found in a variety of habitats, such as forest streams and pools, drains, reservoirs and brackish environments. It can be recognised by a white spot on top of its head, and the lack of bands on its posterior end. This fish feeds primarily on aquatic insects and larvae, and is hence useful in controlling the population of mosquito larvae - it was sometimes introduced into mosquito-prone areas. This gregarious species can grow to about 9cm.

The Striped Panchax (Aplocheilus lineatus) is an introduced species that is occasionally seen in streams and ponds. It can be recognised by the white spot on the top of its head, a generally reddish body, and its posterior end is usually marked with several bands, either complete or disjointed. It can grow to almost 10cm long, though most are shorter. It feeds on aquatic insects and larvae, and sometimes, terrestrial insects that fall into the water and small juvenile fish.


Members of this order generally have elongated bodies and long slender jaws.

Family Hemiramphidae

Members of this family are usually called halfbeaks, as their lower jaws are much longer than their upper jaws. They are usually found just under the surface of the water, and feed on fallen insects.

The Malayan Pygmy Halfbeak (Dermogenys collettei) is a native species that can be found in a variety of habitats, such as acidic forests streams, reservoirs and brackish environments. This surface-dweller can be recognised by its greyish body, shorter upper jaw compare to the much longer lower jaw, and its dorsal fin which begins behind the anal fin. It feeds on fallen insects, and grows to about 6cm long.

The Malayan Forest Halfbeak (Hemirhamphodon pogonognathus) is a native halfbeak that lives in forest streams. It can be differentiated from the previous species by its relatively longer and thinner jaws, the dorsal fin which begins before the anal fin, and the presence of a pair of pale dorsal stripes on the back of many adults. Like other halfbeaks, it lives near the water surface and feeds on fallen insects. It grows to about 10cm long.


Members of this order are very varied in their shapes and sizes, but most have up to four pairs of barbels around their mouths and lack scales. They are usually called catfishes due to the barbels.

Family Clariidae

Clariid catfishes have long scaleless bodies with long-based dorsal and anal fins. The heads appear flattish, while the tail fins range from roundish to squarish. They are air-breathers, and hence are able to survive in waters low in oxygen levels. Some are even able to leave the water to move across land to other water bodies, thus earning them the common name of walking catfishes.

The Common Walking Catfish (Clarias batrachus) is a very adaptable native species that is able to live in a variety of habitats, such as ponds, canals, rural streams, reservoirs and streams in open country. During the rainy season, it can move overland from one water body to another. This species can be recognised by the greyish or brownish body, marked with narrow bands of pale spots. It has a narrow gap between the leading edge of its long dorsal fin and the edge of the bony plates on top of its roundish head, unlike most other similar species which have wider gaps. The adult can grow to about 50cm long. This nocturnal animal uses its four pairs of barbels as sensory organs to find smaller fishes and invertebrates to feed on. In the day, it hides in the soft bottom or among the leaf litter.

The African Sharptooth Catfish (Clarias gariepinus) is an introduced species that is sometimes seen in canals and rivers. It has a large, depressed head with small eyes. The body is greyish or brownish with darker mottles, and lacks the pale spots seen in the previous species. It has four pairs of barbels, and there is a wide gap between the leading edge of its long dorsal fin and the edge of the bony plates on top of its head. This huge fish can grow to about 150cm long. It feeds on small aquatic animals.


This huge order of fishes comprises mostly members possessing dorsal fins with hard and spiny in the front portion, and soft-branching rays towards the rear. In some species, these two portions are split into two separate fins: the spiny dorsal fin and the soft dorsal fin.

Family Eleotridae

Members of this family, commonly called gudgeons, typically have cylindrical bodies with two separate dorsal fins. The pelvic fins are always separated, and most species are bottom dwellers.

Marbled Gudgeon (Oxyeleotris marmorata)
The Marbled Gudgeon (Oxyeleotris marmorata), commonly referred to as Soon Hock in the region, can be found in freshwater swamps, reservoirs and mangroves in Singapore. This nocturnal fish can grow to about 60cm long, and is a popular food fish in Southeast Asia. It is brown with black blotches or bars, allowing it to blend into the surrounding leaf litter and hunt small fishes by ambush.

Family Nandidae

Members of this family are small and laterally compressed. They have large eyes, and usually have colours similar to the leaf litter. Even their body movements mimic dead leaves. These allow them to blend in nicely to the surrounding, allowing them to avoid predation and hunt small aquatic animals by ambush.

Sunda Leaf Fish (Nandus nebulosus)
The Sunda Leaf Fish (Nandus nebulosus) is a native fish found in slow flowing forest streams. It is brown with dark blotches, appearing just like a dead leaf. This species grows to about 13cm long, and hunt small fish and crustaceans by ambush.

Family Osphronemidae

Members of this family are air-breathing and possess thread-like pelvic fins which can be used for sensory purposes. Many species practice parental care for their young.

The Forest Betta (Betta pugnax) is a native fighting fish that lives in clear, shallow forest streams. It can be recognised by its broad-based anal fin which has a pointed tip. The eyes usually have a yellowish ring.

Forest Betta (Betta pugnax)
The colour of the Forest Betta may vary, depending on its mood, ranging from light brown with greenish-blue spots to brown with dark stripes. The male is quite territorial, but not as aggressive as the Siamese Fighting Fish. This species is gregarious and often found in small shoals among the leaf litter or under the vegetation. It feeds primary on small invertebrates. The male brood the eggs in its mouth. This species grows to about 10cm long.

Croaking Gourami (Trichopsis vittata)
The Croaking Gourami (Trichopsis vittata) is sometimes mistaken with the previous species, but can be distinguished by its eyes which have a distinctive blue ring. The snout is generally more pointed, and a few dark horizontal stripes mark the sides of its body. It got its common name from its habit of producing a soft croaking sound during breeding activities. The maximum length of this species is about 6cm, and it is usually found in ponds and streams in rural areas or scrublands.

The Three-spot Gouramy (Trichogaster trichopterus), also spelled "gourami", is a native fish that lives in a variety of habitats, such as slow forest streams, open rural streams, swamps, and ponds with dense vegetation. It can be recognised by the three spots on its body - one being the eye, another near the middle of the body, and the third near the tail. It has a pair of long and thread-like pelvic fins used as tactile organs. This air-breather is omnivorous, feeding on plankton and small invertebrates. It is very popular in the aquarium trade, with many varieties being reared. The adult reaches lengths of about 15cm.

The Snakeskin Gourami (Trichopodus pectoralis) is an introduced species that is native to Thailand has established itself in some rural streams and ponds. It can be recognised by the dark horizontal band running across the middle of its body. This relatively large gourami can grow to about 26cm long, and is sometimes made into dried salted fish for consumption.

Family Anabantidae

Members of this family have a robust body and long-based dorsal and anal fins. They also have obvious spines on their gill covers. They are air breathing, and are well-known for their ability to wriggle over land from one water body to another.

The Asian Climbing Perch (Anabas testudineus) is a native fish that is found in streams and ponds in forests and rural areas, often seen resting on the bottom. It can be recognised by the thickset body, a black spot on its gill cover, and another at the base of the tail. It is able to survive for some time out of water by taking in air and retaining them in a labyrinth organ - a specialised structure in the head for absorbing atmospheric oxygen. When the habitat is damp, e.g. in swampy areas, or after heavy rains, it can "walk" across land by opening the gill plates for support, and pushing itself forward with its strong pectoral, pelvic and tail fins. This species feeds on both plant matter and small aquatic animals. It can grow to about 23cm long.

Family Channidae

Members of this family are commonly called snakeheads, due to their cylindrical body and snake-like heads. They are air-breathing and predatory, but interestingly provide parental care of their young.

The Forest Snakehead (Channa lucius) is a native snakehead which is usually found in shaded forest streams and swamps. It can be recognised by a series of dark blotches along the sides of its body, and an oblique black strip behind the eye. This predatory species feeds on smaller fish, amphibians and aquatic invertebrates. It reaches lengths of about 40cm.

The Common Snakehead (Channa striata), or Aruan, is the commonest native snakehead in Singapore, and occurs in a variety of habitats including slow-moving forest and rural streams, canals, reservoirs, and rural ponds. The body of this fish is brownish above with irregular dark bars, while the underside is white. It is a predatory species, feeding on small fishes, amphibians and invertebrates. It can grow to about 90cm long, and is reared in the region as a food fish. Eating it is believed to aid in the healing of wounds. The adults raise the juvenile fish in a well-protected, underwater nest constructed of vegetation. 

Family Cichlidae

Fishes from this family are native to India, the Middle East, Africa and Latin America, and hence all the ones seen in Singapore are introduced. They are characterised by a laterally compressed body with a continuous dorsal fin. The males are territorial and aggressive towards each other, even though they are generally gregarious in nature. Cichlids are omnivorous, feeding on plant matter and small aquatic animals.

The Mozambique Tilapia (Oreochromis mossambicus) is introduced from Africa to Singapore as a food fish, and has established well in various ponds, canals, reservoirs and tidal rivers. It can be recognised by its thick lips, grey to olive body with a few darker bands/blotches on the sides. Sexually active males are black, and will dig and defend a round burrow to entice the females to breed with it. The female carry the eggs and protects the young in its mouth. This species is omnivorous, feeding on algae, water plants and small aquatic animals. It reaches a maximum length of 40cm.

The Green Chromide (Etroplus suratensis) is an introduced species that is native to India and Sri Lanka. It is a popular aquarium fish, though in the region it is also consumed. It can be recognised by the broad vertical bars on the sides of its body, which are darker below and fade off towards the top. It also has a dark spot at the base of the pectoral fin, and many of the scales have a pearly spot. This fish grows to about 30cm long.

The Mayan Cichlid (Cichlasoma urophthalmus) is an introduced aquarium fish native to Central America. It can be seen in some canals and ponds. This species can be recognised by the black bands on the sides of its body, and a black blotch at the base of the tail. It can grow to about 30cm long.

The Midas Cichlid (Amphilophus citrinellus) is another introduced aquarium fish that is native to South America. It can be recognised by its brownish, orange or reddish coloration and a bump on its fore head. This species grows to about 30cm long.

Threadfin Acara (Acarichthys heckelii)
The Threadfin Acara (Acarichthys heckelii) is another introduced aquarium fish that is native to South Amerrica. It can grow to about 20cm long. It usually has a few long filaments extending from the dorsal fins, and the body is marked with light and dark blotches or bands.


Members of this order, commonly called gars, are native to North and South America, but occasionally individuals released by irresponsible pet owners are found in our waterways.

Family Lepisosteidae

There is only one family in this order, and the members have elongated bodies with thick scales. The jaws are elongated with long and sharp teeth.

The Spotted Gar (Lepisosteus oculatus) is sometimes seen in canals and ponds, released by irresponsible pet owners. They can be recognised by the dark spots densely covering the body, head and fins. This huge fish can attain lengths of about 150cm. It is predatory, feeding on various kinds of small animals.

The Alligator Gar (Atractosteus spatula) is occasionally seen in canals and ponds, released by irresponsible pet owners. This fish can be recognised by its olive brown body that is marked with numerous small dark blotches. This very huge fish can grow to more than 300m long, and feeds on waterfowl, reptiles, amphibians, fishes and crustaceans.

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Wednesday, April 10, 2013

Birds (Phylum Chordata: Class Aves) of Singapore

Birds (phylum Chordata, subphylum Vertebrata, superclass Tetrapoda, class Aves) are air-breathing vertebrates (animals with a backbone and a hollow tube of nervous tissue called a spinal cord) characterised by the possession of feathers. They are descended from four-limbed ancestors (hence the superclass Tetrepoda which means "four legs"), with the two front limbs being modified to become wings.

Many of them have hollow bones, lacking marrow, so as to keep the bird light. A number of their bones are also reduced in size, and many are fused together to form a rigid frame so that the bird will not need not develop large muscles to hold the bones together. All these adaptations, together with the feathered wings and strong flight muscles, allow many birds to be able to fly efficiently.

Birds also have a beak (or bill), which is a hardened structure with upper and lower parts (or mandibles) extending from the mouth, that is used for feeding.

Like the mammals, birds are endothermic, being able to generate body heat and maintain the body temperature within a narrow range. And like many of the reptiles and a few mammals, birds are able to produce water-tight eggs, which are better protected from the external environment compared to the eggs produced by amphibians and fishes.

Here are some examples of birds that are recorded from Singapore:


Waterfowls (order Anseriformes) are birds that have adapted to swimming, and they mostly have a relatively broad bill, long neck, large body, short legs and webbed feet. They include the ducks, geese and swans, some of which are domesticated for human consumption.


Fowls (order Galliformes) refer to chicken or chicken-like birds which usually have colourful feathers, elaborated head skins, feathers and/or other ornaments, and a relatively small head compared to the body. They usually exhibit sexual dimorphism, with the males more brilliantly coloured, or equipped with special feathers and/or other ornaments for courtship display. Some species, such as the chicken, quails, turkeys, pheasants and peacocks, are domesticated either for consumption or as pets.


Charadriiform birds (order Charadriiformes) are very diverse in their appearances and behaviours, though most species live near water bodies (and hence many are called shorebirds) and nest on the ground. Most species are also strong flyers, and migrate over long distances during the winter months. Examples include the plovers, sandpipers, lapwings and terns.


Little Grebe (Tachybaptus ruficollis)
Grebes (order Podicipediformes) are water birds with roundish bodies, small tails and relatively long necks. They are often confused with ducks, but unlike the latter they have pointed bills (instead of broad bills) and toes with leaf-like lobes (instead of webbed feet).  The legs are set towards the back end of the body, allowing them to give powerful kicks with minimum drag, hence making them good swimmers and divers.


Pelecaniform birds (order Pelecaniformes) are mostly birds with relatively long necks (or can stretch it far out), long legs, and short tails (with a number of exceptions). In Singapore, they are represented by the herons and their allies (family Ardeidae), though occasionally rare vagrants like the ibis or free ranging pelicans from the Bird Park can be seen. These birds usually live in wetlands, grasslands and scrublands.


Suliform birds (order Suliformes) are birds with webbed or partially webbed feet, short legs, long wings and long bills. Many are coastal species, and a good number are pelagic birds that spend the major part of their lives out in the open ocean, coming to shore only to breed. Examples include cormorants, frigatebirds and boobies.


Storks (order Ciconiiformes) are birds with long bills, long necks, short tails and long legs. They resemble the herons, but have stouter bills.


Eagles, falcons, kites and other diurnal raptors (order Falconiformes) usually have big hooked bills, strong legs, and long sharp talons on the toes. They generally have excellent eyesight and are very strong flyers. Most are soaring birds, being able to maintain their flight without flapping their wings, but instead ride on the currents created by rising hot air. They are also called birds of prey, since most of them hunt small animals to feed on, though many are also carrion feeders.


Cranes, crakes, rails and their allies (order Gruiformes) are generally ground dwelling birds with long legs and feet but short tails. While cranes are not recorded from Singapore (except the occasional free-ranging ones from the Zoo or Bird Park), a number of rails (family Rallidae) can be found in the country.


Pigeons and doves (order Columbiformes) are birds with a relatively small head, short bill, short neck, stout body and short legs. They mostly eat seeds and/or fruits. Generally there is no real distinction between "pigeons" and "doves", though sometimes the former is used to refer to bigger ones, and the latter, smaller ones. Some people also use "pigeon" for the more frugivorous ones that forage on trees and bushes, and "dove" for those that forage on the ground.


Parrots (order Psittaciformes) are birds with short, rounded, hooked beaks and relatively large heads. They are mostly gregarious and make loud screeching calls. Parrots feed mostly on seeds and fruits, though they may sometimes feed on flowers, pollen, nectar and even insects. Their hooked beaks allow them to easily peel away fruit skins and seed coats, and they have muscular and flexible tongues to help handle and retrieve what they want to eat.


Cuculiform birds (order Cuculiformes) are mostly birds with streamlined bodies, stout beaks and longish tails. In Singapore, they are represented by the cuckoos (family Cuculidae). Many of the species are brood parasites, meaning that they lay their eggs in the nests of other bird species, and the latter will help incubate the eggs and take care of the chicks after they are hatched.


Owls (order Strigiformes) are birds of prey which mostly hunt at night. Depending on the species, they may prey on small mammals, birds, reptiles, insects, crustaceans or fish, which they kill with their powerful talons and sharp, hook-like beaks.


Caprimulgiform birds (order Caprimulgiformes) are nocturnal birds characterised by their relatively large eyes, short necks, short legs, bristles around their mouths, and cryptically patterned, brownish plumage.  In Singapore, this order is represented by the nightjars (family Caprimulgidae), which are more often heard than seen at night due to their loud calls.


Swifts (order Apodiformes) are birds with long, scythe-like wings, short beaks, and often forked tails. They make the fastest powered flights among all flying animals, and usually catch their insect prey on the wing.


Coraciiform birds (order Coraciiformes) are mostly colourful birds which nest in holes. Many species have three forward-pointing toes, with two of the toes fused at the base. Traditionally, they include the rollers, bee-eaters, kingfishers, hornbills and hoopoes, but there have been a number of disputes on the classification of the birds of this order, with studies proposing that some groups should become orders of their own.


Piciform birds (order Piciformes) are mostly arboreal birds which build their nests in tree holes, though some species are brood parasites. Their claws are adapted to hold on to tree trunks and branches, and most species have very stout bills. Examples include the woodpeckers and barbets.


Passerines (order Passeriformes), sometimes called perching birds, are birds adapted to hold on to a perch tightly, even when they are asleep. Three of their four toes are oriented forward, and the remaining one is oriented backwards. And when a passerine lands on a perch, its weight causes the tendons in the leg to tighten and the toes will clamp together tightly, allowing the bird to have a tight grip on the perch.

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