GYMNOTIFORMES - electric fish

  • Family: Sternopygidae
  • Family: Rhamphicthyidae
  • Family: Hypopomidae
  • Family: Apteronotidae
  • Family: Gymnotidae
  • Family: Electrophoridae

    All gymnotiform fish have the same characteristic elongate shape linked to the use of electricity for locating objects.

    Sternopygidae
    There are currently 23 sternopygid species which are grouped on the basis of dentition, skeletal structure and sensory pores. Genera include Distocyclus, Eigenmannia, Rhabdolichops, and Sternopygus. These are essentially nocturnal animals that remain undercover by day. At night they will enter open water in search of prey.


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    Close-up of the head of Distocyclus conirostris
    Close-up of the head of Distocyclus conirostris

    Close-up of the head of Eigenmannia cf. humboldtii
    Close-up of the head of Eigenmannia cf. humboldtii

    Close-up of the head of Eigenmannia virescens
    Close-up of the head of Eigenmannia virescens

    Close-up of the head of Eigenmannia macrops
    Close-up of the head of Eigenmannia macrops

    A recently caught specimen of Rhabdolichops caught in an eel trap in a white water river channel
    A recently caught specimen of Rhabdolichops caught in an eel trap in a white water river channel

    Close-up of the head of an Eigenmannia sp
    Close-up of the head of an Eigenmannia sp

    Close-up of the head of an Eigenmannia sp
    Close-up of the head of an Eigenmannia sp

    Close-up of the head of an Eigenmannia sp
    Close-up of the head of an Eigenmannia sp

    Close-up of the head of a Rhabdolichops species
    Close-up of the head of a Rhabdolichops species

    Photograph of the anterior half of a Rhabdolichops species
    Photograph of the anterior half of a Rhabdolichops species

     

    Photograph of the anterior half of a Rhabdolichops species
    Photograph of the anterior half of a Rhabdolichops species

     

    Photograph of the anterior half of a Rhabdolichops species
    Photograph of the anterior half of a Rhabdolichops species

     


    Rhamphichthidae
    There are currently 13 described species in this family. These are divided between three genera, Rhamphichthys, Gymnorhamphichthys and Iracema.


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    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk
    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk

    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk
    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk

    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk. This specimen was caught in Lake Tefe in an open water gill net
    Close-up of the head of species of a Rhamphichthys species showing the characteristic trunk. This specimen was caught in Lake Tefe in an open water gill net

    Living specimen of Gymnorhamphichthys rondoni
    Living specimen of Gymnorhamphichthys rondoni

    A large Rhamphichthys specimen caught in a gill net in Lake Tefe. This fish must have been swimming in open water when it was caught. This specimen was caught in Lake Tefe in a gill net set in open water.
    A large Rhamphichthys specimen caught in a gill net in Lake Tefe. This fish must have been swimming in open water when it was caught. This specimen was caught in Lake Tefe in a gill net set in open water.

       

    Head of a large Rhamphichthys specimen caught in a gill net in Lake Tefe. This fish must have been swimming in open water when it was caught. This specimen was caught in Lake Tefe in a gill net set in open water.
    Head of a large Rhamphichthys specimen caught in a gill net in Lake Tefe. This fish must have been swimming in open water when it was caught. This specimen was caught in Lake Tefe in a gill net set in open water

      


    Hypopomidae
    Hypopomidae are electric or knife fish, and like other gymnotiform fish have the same characteristic elongate shape linked to the use of electricity for locating objects. This family possesses long tails, which can become very long in the males because the females assess the quality of their mates by the length of their tails! This happens because the electrical signals sent out by the male change with the length of the tail. Poor quality males loose their tails to piranha attack, but all is not lost, as they will re-grow. There are currently 16 species in the Hypopomidae and these are assigned to the genera Hypopomus, Brachyhypopomus, Microsternarchus, Steatogenys and Hypopygus. The members of this family tend to live within aquatic substrates such as leaf litter or floating meadow. They are often highly resistant to low oxygen levels. They have small mouths and feed on micro-crustaceans, small insects such as chironomids and other micro-invertebrates.


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    Living specimen of Hypopygus lepturus
    Living specimen of Hypopygus lepturus

    Close-up of the head of Brachyhypopomus beebei
    Close-up of the head of Brachyhypopomus beebei

    Close-up of the head of Brachyhypopomus brevirostris
    Close-up of the head of Brachyhypopomus brevirostris

    Close-up of the head of Brachyhypopomus pinnicaudatus
    Close-up of the head of Brachyhypopomus pinnicaudatus

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Close-up of the head of a member of the Hypopomidae
    Close-up of the head of a member of the Hypopomidae

    Lateral view of a preserved specimen of the electric fish Steatogenys elegans
    Lateral view of a preserved specimen of the electric fish Steatogenys elegans

    Hypopomus species found in leaf litter
    Hypopomus species found in leaf litter

    Hypopomus species found in leaf litter
    Hypopomus species found in leaf litter

    Hypopomus species found in leaf litter
    Hypopomus species found in leaf litter

     


    Apteronotidae
    This family differs from other knife fish in the possession of a distinct tail fin and a long filamentous dorsal fin. At present there are 36 species in this family.


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    Whole specimen of Apteronotus hasemani which was caught in an eel trap in a white water floodplain channel
    Whole specimen of Apteronotus hasemani which was caught in an eel trap in a white water floodplain channel

    Close-up of the head of a preserved specimen of Apteronotus bonapartii
    Close-up of the head of a preserved specimen of Apteronotus bonapartii

    Close up of the head of Apteronotus anas
    Close up of the head of Apteronotus anas

     

    Whole specimen of Apteronotus albifrons
    Whole specimen of Apteronotus albifrons

    Close up of the head of Sternarchella cf. terminalis
    Close up of the head of Sternarchella cf. terminalis

    Close up of the head of Sternarchogiton porcinum
    Close up of the head of Sternarchogiton porcinum

    Close up of the head of Platyurosternarchus macrostomus
    Close up of the head of Platyurosternarchus macrostomus



    Gymnotidae
    In this family, only the pectoral and anal fins are present. The family comprises a single genus, Gymnotus, which holds some of the most abundant and familiar knife fish from the Amazon. This genus is widely distributed in almost all forest and floodplain habitats. They possess large mouths for knife fish and are active nocturnal predators on insects, prawns and fish. Their bodies often have a black and white banded or even spotted pattern. Recent taxonomic revisions have placed the electric eel, Electrophorus within this family.

    G. carapo
    Identification: A deep-bodied knife fish reaching a length of more than 20 cm. It is the only species within the Taruma-Mirim with vertical banding along the full length of the body. It has a large mouth.
    Colour: dark background with white bands.
    Habitat: Leaf-litter banks, root mats and floating meadow
    Abundance: Widely distributed within the Amazon and abundant in varzea. Seems not to be particularly common in the Taruma-Mirim.
    Food: Active predator. Young feed on insects and crustaceans. Adults will also take fish.

    Gymnotus sp1
    A large mouthed robust knife fish much like Gymnotus carapo in form but thinner bodied. Only the rear 1/3 to 1/2 of the body is banded. It is similar to G. angularis in general form.


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    Close-up of the head of a preserved specimen of Gymnotus carapo
    Gymnotus carapo

    Close-up of the head of a preserved specimen of Gymnotus anguillaris
    Close-up of the head of a preserved specimen of Gymnotus anguillaris

    Close-up of the head of an unidentified Gymnotus species
    Close-up of the head of an unidentified Gymnotus species

    Close-up of the head of an unidentified Gymnotus species
    Close-up of the head of an unidentified Gymnotus species

    Close-up of the head of an unidentified Gymnotus species
    Close-up of the head of an unidentified Gymnotus species

    Close-up of the head of an unidentified Gymnotus species
    Close-up of the head of an unidentified Gymnotus species

    A Gymnotid electric fish found in submerged leaf litter
    A Gymnotid electric fish found in submerged leaf litter

    Close-up of the head of a Gymnotid electric fish found in submerged leaf litter
    Close-up of the head of a Gymnotid electric fish found in submerged leaf litter

    A Gymnotid electric fish found in submerged leaf litter
    A Gymnotid electric fish found in submerged leaf litter

     

    A Gymnotid electric fish found in submerged leaf litter
    A Gymnotid electric fish found in submerged leaf litter

     


    Electrophoridae
    This family holds a single species, the famous electric eel, Electrophorus electricus. This is the only gymnotiform fish to generate powerful electric shocks and is by far the largest species of electric fish found in the Amazon. The electric discharge from this species is sufficient to knock a man from his feet and I have known biologists to be unable to walk properly for a day after being shocked. This is a widely distributed species found in both white and black waters in both flood plain lakes and small forest streams. It is a top predator of the system and is surprisingly abundant. It probably favours hunting along the margins of flooded forest and within forest streams. We found that eel traps placed within flooded forest close to the water margin caught a surprising number of specimens. When the water is rising, they lurk round the edge of islands ready to catch snakes, frogs and other animals as they are forced to enter the water. Electric eel often lie close to the surface and have the menacing presence of a nuclear hunter killer submarine; they are often quite indifferent to predatory threats. While working on leaf-litter banks in small streams, I have suddenly realized that a large specimen has silently moved close by, perhaps attracted by the disturbance. Thankfully, they do not discharge unless threatened or during capture of their prey.


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    The head of the electric eel, Electrophorus electricus, near to the surface of the water
    The head of the electric eel, Electrophorus electricus, near to the surface of the water

    A living specimen of the electric eel, Electrophorus electricus
    A living specimen of the electric eel, Electrophorus electricus

    A living specimen of the electric eel, Electrophorus electricus
    A living specimen of the electric eel, Electrophorus electricus

    A living specimen of the electric eel, Electrophorus electricus
    A living specimen of the electric eel, Electrophorus electricus