CYPRINIFORMES - carps and characins: Page 6

  • Family: Characidae
    The largest family of characiform fish. They are variable in shape and habit. Characins do not have barbels, but most have an adipose fin, and well-developed teeth. Some workers include the Serrasalmidae within this family. While they are clearly closely related to genera included within the Characidae, I have separated them here for convenience, more than good taxonomic reasons. The family includes many genera, including Astyanax, Moenkhausia, Chalceus, Charax, Iguanodectes, Brycon, Acestrorhynchus, Hyphessobrycon, Paracheirodon, Poptella, Prionobrama, Rhaphiodon, Roeboides, Tetragonopterus, and Triportheus.

    Astyanax
    This genus is distinguished from other tetra genera by the possession of a continuous lateral line. One of the commoner species is Astyanax bimaculatus, the two-spot tetra, which can grow to about 15 cm in length.
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    Lateral view of a preserved specimen of Astyanax bimaculatus
    Lateral view of a preserved specimen of Astyanax bimaculatus

    Moenkhausia
    This genus holds a number of attractive, small, tetra species. They tend to be general predators feeding on small invertebrates. They are often abundant in shallow bays and inlets within floodplain white water lakes and other habitats unsuitable for large fish, such as small forest streams.
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    Lateral view of a preserved specimen of a Moenkhausia sp.
    Lateral view of a preserved specimen of a Moenkhausia sp.

    Chalceus
    These are small to medium sized fish attaining a maximum size of about 25 cm. The scales are unusually large and the body a rather dull silver-green. The fins, however, are often colourful being bright red or red-yellow in Chalceus erythrurus. This species is a common flood plain species and is rarely absent from surface waters. It patrols in small groups and will take a wide variety of foods.
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    A recently caught specimen of Chalceus erythrurus
    A recently caught specimen of Chalceus erythrurus

    Charax
    These are pale, almost transparent fish with the head placed oddly so that the body rises in a high hump behind the head. They are called hump-backed head standers because they swim looking down at an angle onto the substrate. The only significant area of pigmentation on the body of C. gibbosus and related species is a black blotch on the shoulder. Charax spp. are general invertebrate predators and are abundant and widely distributed in both main river channels and the flood plain lakes.
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    Lateral view of a preserved specimen of Charax sp. - probably C. gibbosus
    Lateral view of a preserved specimen of Charax sp. - probably C. gibbosus

    Iguanodectes
    These are elongate tetras living in open water. Iguanodectes spilurus is a common, although never abundant, fish. It is fast moving and an able jumper. It is rather dull in colouration; the upper lobe of the tail carries a black blotch.
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    Iguanodectes spilurus - Lateral view of preserved adult specimen
    Iguanodectes spilurus - Lateral view of preserved adult specimen

    Brycon
    This genus comprises medium-sized open water fish which are abundant in floodplain lakes and channels. One of the commonest species is B. melanopterus which has a characteristic black diagonal strip running down from the tail and across the body. They are active feeders taking a wide range of foods including insects, flowers, fruits and seeds.
    Brycon sp. gut contents (P=present)
    INDIVIDUAL NUMBER 1 2 3 4 5
    LENGTH (cm) 16 16 18.5 17 16.5
    MASS (g) 78 82 105 95 92
    EPHEMEROPTERA   1      
    LEPIDOPTERA 6        
    PLANT-SEEDS INDET.   8      
    CECROPIA LOTILOBA   40      
    RHEEDIO MACROPHYLLA     2 3  
    BROSIMUM LACTESCENS   1 1   7

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    A photograph of a preserved specimen of Brycon melanopterus
    A photograph of a preserved specimen of Brycon melanopterus

    A photograph of a preserved specimen of Brycon melanopterus
    A photograph of a preserved specimen of Brycon melanopterus

    Paintings of Brycon melanopterus made by Peter Henderson in the field, illustrating the colouration of the fins and the damage caused to the tail by piranha attack
    Paintings of Brycon melanopterus made by Peter Henderson in the field, illustrating the colouration of the fins and the damage caused to the tail by piranha attack

    Acestrorhynchus
    These are the pike characins, with the large teeth and elongate bodies of typical piscivores. They are abundant fish in flood plain lakes and channels and are frequently caught in open water. Their shape would suggest that they hunt as an ambush predator, however at low water they seem to hunt actively as they are often caught in open water using floating gill nets.
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    Close-up of the head of Acestrorhynchus falcatus showing the sharp teeth
    Close-up of the head of Acestrorhynchus falcatus showing the sharp teeth

    The open water predators of an Amazonian lake. All three species shown in the photograph were caught in the same net. From top to bottom, the species shown are Rhaphiodon vulpinus, Acestrorhynchus falcatus and Hydrolycus sp.
    The open water predators of an Amazonian lake. All three species shown in the photograph were caught in the same net. From top to bottom, the species shown are Rhaphiodon vulpinus, Acestrorhynchus falcatus and Hydrolycus sp.

    Hyphessobrycon
    A genus of typical small tetras, many with attractive fin patterns.

    Paracheirodon
    P. innesi is a small tetra, familiar to many as the neon tetra. It is a fish of great beauty although no longer appreciated as fully as it should be because of familiarity. It is found naturally in the upper Amazon, close to the Peruvian border. Like a number of other colourful tetras it lives in small black water forest streams. Presumably, within clear but stained water, with a gentle light filtered through the trees, the colours of this fish are optimal for high visibility. It is a small tetra with a maximum length of about 4 cm.

    Poptella
    P. orbicularis is frequently caught in floating meadows and is probably associated with areas rich in vegetation. It is a larger than average, deep bodied, tetra.
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    Lateral view of a preserved specimen of Poptella orbicularis
    Lateral view of a preserved specimen of Poptella orbicularis

    Prionobrama
    These are rather elongate tetras. Within the Amazon floodplain Prionobrama filigera is common, but never abundant. It also lives in small tributaries. This species is an active swimmer and attains a length of about 6 cm. On account of the fin colouration it is called the Glass Bloodfin.
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    Lateral view of a recently caught specimen of Prionobrama filigera
    Lateral view of a recently caught specimen of Prionobrama filigera

    Rhaphiodon
    This genus holds two remarkable fish: Rhaphiodon gibbus and R. vulpinus, which are both found together and are quite similar except for the fact that R. vulpinus has a proportionately longer body. Upon first catching one of these fish the impression is that the head and the body are mismatched. There is a hump on the dorsal surface at the neck and the mouth points upwards. The next feature that is noticed is the remarkable length of the teeth. These species are open water piscivores and the teeth are evidently used to kill their prey although it is difficult to understand the particular advantage offered by their shape and dentition. The only colouration on the generally silvery body is a black blotch behind the head. Both species are common within the Amazonian floodplain.

    They were once placed in their own family, the Cynodontidae.
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    Lateral view of a preserved specimen of Rhaphiodon gibbus
    Lateral view of a preserved specimen of Rhaphiodon gibbus

    Lateral view of a preserved specimen of Rhaphiodon vulpinus
    Lateral view of a preserved specimen of Rhaphiodon vulpinus

    The open water predators of an Amazonian lake. All three species shown in the photograph were caught in the same net. From top to bottom, the species shown are Rhaphiodon vulpinus, Acestrorhynchus falcatus and Hydrolycus sp.
    The open water predators of an Amazonian lake. All three species shown in the photograph were caught in the same net. From top to bottom, the species shown are Rhaphiodon vulpinus, Acestrorhynchus falcatus and Hydrolycus sp.

    Roeboides
    The members of this genus are distinctive white bodied fish which are laterally compressed and have a hump behind the head. They often swim with the head looking down, but do not take food off the bottom as they are scale feeders. To rip the scales from other fish they have teeth on the outside of the lips.
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    Lateral view of a recently caught Roeboides species
    Lateral view of a recently caught Roeboides species


    Tetragonopterus
    There are a number of genera holding the small tetras which are so abundant in Amazonia. These small fish can be seen in the margins of almost all Amazonian waters and become particularly abundant in small forest streams where they will come to any disturbance in the hope of food. They can be attracted (and fed) just by wiggling your fingers in the water which they will soon investigate and start removing any damaged skin. If you keep this activity up long enough you will attract their bigger cousins the piranhas and possibly lose the end of a finger or two!
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    A typical tetra. Lateral view of an unidentified species found in white water lakes
    A typical tetra. Lateral view of an unidentified species found in white water lakes

    A typical tetra. Lateral view of an unidentified species
    A typical tetra. Lateral view of an unidentified species

    A typical tetra. Lateral view of an unidentified species
    A typical tetra. Lateral view of an unidentified species

    A typical tetra. Lateral view of an unidentified species
    A typical tetra. Lateral view of an unidentified species

    Triportheus
    The members of this genus are adapted for life close to the water surface. They generally feed off the surface collecting small insects, pollen and a wide range of vegetable matter. When frightened they are able to make their escape by rising above the surface like a hydrofoil on their deep keels and rowing themselves along with their powerful pectoral fins. There are three Amazonian species which are all abundant in floodplain lakes, Triportheus albus, Triportheus angulatus, and Triportheus elongatus. Any visitor during a boat trip in a white water lake will see one of these species.
    Triportheus angulatus gut contents (P=present)
    INDIVIDUAL NUMBER 1 2 3 4 5 6 7 8 9 10
    LENGTH (cm)   13 13 14.5 14.3 11.3        
    MASS (g)   48 40 48 58 24        
    ARTHROPODA-INDET.             P      
    HYMENOPTERA             1 P P P
    LEPIDOPTERA 1                  
    ODONATA                 2  
    ORTHOPTERA             P P    
    PLANT-SEEDS INDET. 10 3       3        
    FICUS   10                
    MYRCIA     7              
    CECROPIA LOTILOBA       20 200 75     P P

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    Lateral view of recently caught adult Triportheus angulatus
    Lateral view of recently caught adult Triportheus angulatus

    Close-up of a living specimen of Triportheus angulatus
    Close-up of a living specimen of Triportheus angulatus

    Lateral view of recently caught adult Triportheus angulatus
    Lateral view of recently caught adult Triportheus angulatus

    Lateral view of a recently caught specimen of Triportheus elongatus
    Lateral view of a recently caught specimen of Triportheus elongatus