TankBud

Banded knifefish

Gymnotus carapo

Also known as Carapo knifefish, Tuvira

FreshwaterFish

Banded knifefish (Gymnotus carapo)
Naturalist_on_the_River_Amazons_figure_21.png: Unknown authorUnknown author derivative work: Haplochromis (talk) · Public domain

Care at a glance

Temperature
73–82°F
23–28°C
pH
6.0–7.5
Adult size
15.7 in
40 cm
Minimum tank
79 gal
300 L
Temperament
Aggressive
Social behavior
Solitary
Own kind
One per tank
Tankmates
With caution
Swim level
Bottom
Diet
Carnivore
Difficulty
Medium
Breeding
Hard
Rarity
Rare
Family
Gymnotidae
Origin
Native to slow rivers, floodplains and swamps across much of South America, hiding among submerged roots and leaf litter.

Overview

The banded knifefish is a predatory electric fish for the bottom of a large, dim tank. It is best with a little experience.

Did you know

The banded knifefish reads its surroundings with a self-generated electric field, so it can hunt and steer in complete darkness.

Caring for the banded knifefish

Give a banded knifefish at least 79 gal (300 L), with plenty of caves, wood and dim lighting. Keep the water at 73 to 82°F (23 to 28°C), with a pH of 6.0 to 7.5.

It is active mainly at night, so feed it after dark. Offer earthworms, prawns, bloodworm and other meaty foods.

The banded knifefish is predatory and territorial, so keep one per tank. Choose any tank mates with caution, and only fish too large to eat. Breeding it is hard.

Good to know

Gymnotus carapo belongs to the family Gymnotidae. Its tapering, knife-like body is banded in brown and cream. It swims by rippling a long fin under the body, moving smoothly forward or backward. It also uses its weak electric discharge for communication in dark, murky water. It is an air-gulping fish, and wild fish occasionally grow larger than the usual 15.7 in (40 cm).

In the wild

The banded knifefish lives in slow rivers, floodplains and swamps across much of South America. It hides among submerged roots and leaf litter.

Common questions

What size tank does a banded knifefish need?

A banded knifefish needs at least 79 gal (300 L). It spends most of its time in the bottom.

What temperature and pH does a banded knifefish need?

A banded knifefish is comfortable at 73–82°F (23–28°C) with a pH of 6.0–7.5.

What does a banded knifefish eat?

A banded knifefish eats earthworms, prawns, bloodworm and other meaty foods. Feed it after dark, since it is active mainly at night.

How big does a banded knifefish get?

An adult banded knifefish reaches about 15.7 in (40 cm).

Related species