• Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)
  • Glass Knifefish (Eigenmannia virescens)

Glass Knifefish (Eigenmannia virescens)

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* For the safety of our animals, we now ship live fish exclusively via UPS Next Day Air.  If your order contains this item, you will only see UPS Next Day Air as a shipping option during checkout * 


The Glass Knifefish is a relatively uncommon, but fascinating "oddball" fish in the freshwater aquarium hobby!


The Glass Knifefish (Eigenmannia virescens) is a very unique and remarkable fish that is native to many waterways in South America. This species gets its name from its "glasslike", transparent body. Though this species resembles the popular Black Ghost Knifefish, it is a different genus. It is still a knifefish and possesses similar characteristics as far as body shape and movement. This fish swims by use of undulating movement of its very long anal fin and is able to swim in reverse as easily as swimming forward. It is a nocturnal predator and perceives its surroundings and prey by producing an extremely weak electrical pulse, which cannot be felt by other animals that do not produce this pulse.


The Glass Knifefish requires an aquarium with plenty of cover such as plants, driftwood, rock formations, or various forms of plastic or glass tubing. A sandy substrate and floating plants are also optimal. It is a relatively peaceful species with other fish and invertebrates too large to be considered prey.  Unlike many knifefish in the Apteronotus genus, Glass Knifefish actually prefer to be housed and will actually school with conspecifics. At a maximum size of 16 inches, it reaches a similar size as the Black Ghost Knifefish. That being said, a 125 gallon aquarium is recommended though a larger footprint is more important that height.  Powerful filtration and regular aquarium maintenance are also necessary for this predatory fish.


In the wild, the Glass Knifefish feeds on small invertebrates and fish. It has a relatively small mouth for a fish of its size, but it should still not be trusted with much smaller fish and invertebrates in the aquarium. Our specimens are currently feeding on a variety of frozen and live meaty foods and some will also take high-quality dry foods. 


What We Like About This Fish:
  • Extremely unusual appearance
  • Unique swimming behavior
  • Relatively peaceful with most other fish of appropriate size
  • Uncommon oddball species
  • Will not bother plants 


  • Temperature:  68°- 86° F (20° - 30° C)
  • pH:  6.0 - 7.5
  • KH:  5 - 10 dKH
  • Minimum tank size:  125+ gallons for a full-grown adult
  • Diet:  Carnivorous. Requires a varied died of frozen, live, and dry meaty foods
  • Social behavior:  Peaceful with most animals that inhabit other areas of the water column and are too large to be considered prey. Prefer to be housed in groups.
  • Origin: Indigenous to Amazon Basin
  • Average adult size:  Up to 16 inches (40.6 cm)
  • Average purchase size:  3 - 5 inches (7.6 - 12.7 cm) 

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