Javari banded knifefish

Care at a glance

Overview

Keep this electric knifefish one to a tank, without exception, because it is aggressive toward its own kind and other knifefish and will fight them. It hunts at night along the bottom, threading through leaf litter and roots, and navigates by a weak electric field. It is best in a species tank or with tankmates chosen very carefully: peaceful fish too large to swallow can work, but small fish and shrimp will be eaten. Give it soft, warm water, dense cover, and plenty of hiding tubes. Feed meaty foods in the evening: frozen bloodworm, blackworm, chopped prawn, earthworm, and sinking pellets. Allow at least 250 litres with lots of shelter.

In the wild

It comes from the Javari basin on the Peru and Brazil border, hunting in slow, leaf-choked backwaters and margins in soft, warm, tannin-stained water. Recreate that with warm water of 24 to 28 degrees Celsius, a soft, acidic to neutral pH of 5.5 to 7.2, gentle flow, dim light, and dense cover of driftwood, roots, and leaf litter with tubes to hide in by day.

Good to know

It belongs to the banded knifefish family, Gymnotidae, and reaches about 20 cm, marked with oblique dark bands along a tapering body. Like its relatives it produces a continuous weak electric discharge that it uses to navigate, find prey, and signal to other fish. There is no established record of it spawning in aquaria.

Did you know

When two of these knifefish meet, their electric discharges can clash. If their signals are too close in frequency, each fish shifts its own so the two no longer interfere, a built-in reaction that keeps their electric senses working side by side.

Common questions

Related species

• 

  Banded knifefish

  Gymnotus carapo

  Freshwater

  15.7 in (40 cm)79 gal (300 L)73–82°F (23–28°C)
• Lyons' cichlid

  Amphilophus lyonsi

  Freshwater

  7.1 in (18 cm)106 gal (400 L)75–84°F (24–29°C)

• 

  Chameleon loach

  Syncrossus beauforti

  Freshwater

  9.8 in (25 cm)106 gal (400 L)73–82°F (23–28°C)
• Spotted algae eater

  Gyrinocheilus pennocki

  Freshwater

  11 in (28 cm)53 gal (200 L)72–82°F (22–28°C)

• 

  Common jewel cichlid

  Rubricatochromis guttatus

  Freshwater

  5.5 in (14 cm)66 gal (250 L)73–81°F (23–27°C)

• 

  Hairy Puffer

  Tetraodon baileyi

  Freshwater

  5.5 in (14 cm)26 gal (100 L)73–81°F (23–27°C)