Gnathonemus petersii (Gunther, 1832)
Suggested pronunciation: nath-oh-NEEM-uss peters-eye

Species description

• Physical description....
• The Elephantnose has a long, laterally compressed and almost rectangular body.
• The mouth and eyes are small.
• The mouth is located above the sensory organ extending from the chin.
• They have a mostly dark grey, almost black body with a white line and a white crescent near the rear of the body.
• The vertical white stripe bisects the body at the base of the dorsal and anal fins.
• The dorsal fin is set far back on the body, meeting the tail.
• The anal fin matches this position on the ventral side.
• The fins are edged in white.
• The Elephantnose has a large head and a finger-like extenion on the lower jaw.
• The caudal fin is set on a very thin caudal peduncle.
• The pectoral fins are almost flipper-like and the pelvic fins are relatively small.
• This is a very unusual and exotic looking fish.
• Taxonomy....
• Kingdom: Animalia
  • Phylum: Chordata: Sub-phylum: Vertebrates - Group: Fish
    • Class: Osteichthyes (Bony Fish): Sub-class: Actinopterygii (Ray-finned Fish)
      • Order: Osteoglossiformes (Bonytongues)
        • Family: Mormyridae (Elephantnoses)
          • Genus: Gnathonemus
            • Species: petersii
• Geographical variants....
  • None.
• Similar species....
• There are other fish known as Elephantnoses (eg. Campylomormyrus rhynchophorus - Double nose Elephantnose or Angolan Downpoker), but none look like Gnathonemus petersii.
• Gnathonemus petersii has a flatter forehead profile than the more steeply curved forehead of Campylomormyrus.
• Gnathonemus petersii is a more uniform black colour and has a single "Elephantnose".
• Images:
  • Gnathonemus petersii (below left); Campylomormyrus rhynchophorus (below right)

• Another Mormyrid that is available in Queensland is Marcusenius macrolepidotus (Freshwater Dolphin), which belonged to the genus Gnathonemus.

Habitat information

• Gnathonemus petersii is found in slowly moving water near submerged wood in the rivers of West and Central Africa - Congo, Nigeria and Cameroon.
• They are restricted to the Lower Niger basin, in the Ogun River, in the Cross River Basin and in the upper Chari River.

Aquarium care
The following information relating to tank size, decoration and tank mates is indicative and intended to be used as a rough guide only.
Most of the information under tank ideas relates to setting up a biotope tank - where the fish and plants all come from the same region or country (eg. the Rio Xingu or Southeast Asia).
Other possible tank mates are listed under Compatibility and there are many plants and decorations that can be used - just ask us.

• Tank ideas....
• A tank of around 90 centimetres (36 inch) is a recommended minimum size for sub-adult fish.
• To keep a group of adults a tank of dimensions 120x38x45cm (48x15x18 inches) or 205 litres would be suitable.
• Example biotope - West African Floodplain Swamp
  This tank represents a permanent swamp habitat that develops on the African floodplain. These areas are characterised by a dark, shadowy look, soft water and plenty of vegetation.
  
  • Tank capacity: 363 litres
  • Tank type: HR-1500B
    • 150 centimetres (60 inches or 5 foot) tank
    • 3 x 40W fluorescent tubes
  • Fish ideas:
    • 3 x Gnathonemus petersii
    • 2 x Pelvicachromis pulcher
    • 3 x Ctenopoma acutirostre
    • 12 x Alesteopetersius caudalis
  • Building the tank:
    • Background - external printed black.
    • Substrate - 3mm black gravel, river sand and peat moss; roughly 50:20:5kg ratio - mix the sand and peat through the gravel.
    • Decoration - Driftwood to create tangled branch effect; bark tunnel; scattered smooth rocks. Create plenty of hiding places to give each Elephantnose their own cave. Attach the Anubias to some of the rocks.
      
    • Plants - Suitable plants include Hairgrass (Eleocharis acicularis), Anubias barteri , Straight Val (Vallisneria spiralis) and Red Tiger Lotus (Nymphea maculata).
      
• Maintenance and Disease....
• Elephantnoses are intolerant of medication and salt.
• They are susceptible to white spot, so prevention is best - ensuring the water temperature is around 26oC, regular partial water changes and minimising stress.
• They are extremely sensitive to water quality changes.
• Good filtration is necessary as they produce large amounts of nitrogenous waste. They also feel more comfortable with slight water movement in the tank.
• The substrate should be a fine rounded gravel, as these fish spend most of their time searching for food in the gravel.
• Don't use sharp rocks, wood or ornaments as they may damage their scaleless bodies.
• Plants help to make them feel more secure and to dim the tank.
• They don't maintain permanent territories,regularly moving from cave to cave, so it is important to provide plenty of hiding spots to allow the weaker fish to find shelter when they are threatened.
• Caves and hiding places are needed to minimise interference from the electrical fields. The fish get stressed if they are in constant contact with each other's electrical field.
• The tank must have lids as Elephantnoses will jump, particularly within the first 24 hours after being introduced to the tank. Floating plants can help to reduce this jumping as well.
• They shouldn't be overfed, but you need to make sure that they are getting enough food, especially if there are fast middlewater fish such as Tetras in the tank with them. Because they have small mouths, you also need to make sure that the food size is small enough for them.
• It is a good idea to feed just before turning the aquarium lights off so that the Elephantnose gets enough to eat.
• When they are settled into the tank, they can be a playful fish and you will start to see them moving around and searching for food during the day.
• Water parameters:
  
• pH: slightly acidic to slightly alkaline (6.0-7.2: optimum 6.7)
  
• Hardness: soft (3-12dH: optimum 7)
• Temperature: 24-28oC.
  
• Compatibility....
• Gnathonemus petersii is peaceful towards other fish. Because they have a small mouth, even the smallest fish won't be eaten.
• Elephantnoses have their own hierarchy system and dominant animals will chase submissive ones.
• They should not be combined with aggressive fish.
• It is often recommended that only one Elephantnose per tank be kept.
• However, with the right tank set-up that provides plenty of hiding places for each fish, a group of Elephantnoses can be kept.
• They should be kept in a group of 3 or more.
• They seem to be more outgoing when kept in a group.
• They are an inquisitive fish that will check out anything new in their tank.
  
  

  Ideas for suitable tankmates.... The fish listed below are indicative of the species that can be kept with this fish. Other fish may also be suitable - please ask us which other fish are compatible. ______________________________ Africa - Riverine Congo Tetra (Phenacogrammus interruptus) Kribensis (Pelvicachromis pulcher) Upside-down Catfish (Synodontis nigriventis) African Butterflyfish (Pantodon buchholzi) Synodontis brichardi Steatocranus tinanti African Knifefish (Xenomystus nigri) ______________________________ South America Discus (Symphysodon aequifasciata) Red Hump (Geophagus steindachneri) Blue Ram (Microgeophagus ramirezii) Keyhole Cichlid (Cleithracara maroni) Silver-tip Tetra (Hasemania nana) Kerri Tetra (Inpaichthys kerri) Royal Whiptail (Sturisoma aureum) ______________________________ Asia Chocolate Gourami (Sphaerichthys osphromenoides) Gold Barb (Puntius schuberti) Silver Shark (Balantiocheilus melanopterus) Pearl Gourami (Trichogaster leeri)

• Breeding....
• Unknown.
• This species has not been bred in captivity.
• The Elephantnose is one of those fish that is frequently found in aquariums but serious breeding attempts don't seem to have been made.

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• References....
  Web sites
  Fishbase
  Books
  The Aquarium Fish Handbook (Silverdale Books, 2002)
  Baensch Aquarium Atlas (Mergus, 1996)
  Encyclopedia of Fishes (Fog City Press, 2004
  Popular Freshwater Tropical Fish (Parragon, 2002)
  The Complete Encyclopedia of Tropical Fish (Grange Books, 2000)
  

WetPetz
ph: (07) 3823 1866