Banded Knifefish
Gymnotus carapo
A massive, eel-like nocturnal predator reaching 60 cm. Strikingly decorated with yellow and black tiger stripes. Incredibly hardy (breathes air), but notoriously aggressive and entirely intolerant of any other knifefish. A true 'Monster Fish'.
Temperatura da água
22 - 28 °C
Valor de pH
6 - 7.5
Tipo de água
Água doce
Nível do tanque
Parte inferior e intermediária
Tamanho adulto
60 cm
Volume mínimo do tanque
>= 500 L
Grupo mínimo
>= 1
GH
4 - 15 dGH
KH
2 - 7 dKH
TDS
80 - 295 ppm
Condutividade
125 - 461 uS/cm
Descrição da espécie
Geographical Origin and Habitat: Omnipresent in the Amazon and Orinoco basin. Nocturnal predator of shady swamps, flooded forests (Igapó) and trickles saturated with decomposed vegetation. Capable of surviving in stagnant waters almost devoid of oxygen.
Taxonomy and Morphology: Banded Knifefish. Cylindrical and tapered shape similar to an eel, but compressed laterally. Totally devoid of dorsal, caudal and pelvic fins: it moves by undulating the immense anal fin forwards and backwards. Reaches 60 cm (24 inches).
Social Behavior: Ruthless, intolerant and solitary. Generates a weak continuous electric field to hunt and communicate in total darkness. If two Gymnotus are placed in the same tank, they will attack each other with inhuman ferocity until the death of the weaker.
Coloration and Sexual Dimorphism: Formidable camouflage. Chestnut or chocolate brown body crossed by narrow yellowish or beige oblique bands, which thicken towards the tail. Very small eyes. Impossible to distinguish the sexes visually.
Cuidado, criação e companheiros de tanque
Aquarium Setup: Tank for large predators (minimum 150 cm / 5 feet / 500 liters). STRICTLY requires large PVC pipes or hollow logs in which to hide perfectly during the day. Very low lights. Insert floating plants and ensure a very heavy lid: it is capable of smashing the glass to jump.
Diet and Feeding: Pure carnivore and ambush predator. Hunts at night swallowing whole fish. Must be fed with lights off with giant earthworms, crayfish, mussels and large insects. Rarely accepts pelleted feeds.
Water Quality: Primitive fish, capable of breathing atmospheric air if water is scarce (obligate aerial respiration). It is literally indestructible from a chemical point of view, enduring very high pollutant loads, acidic pH and temperatures from 22 to 28°C (71-82°F).
Compatibility and Cohabitation: Nocturnal fish-eater (Nightmare for tankmates). Any fish that enters its mouth will be devoured at night (including Tetras, Corydoras and young Cichlids). Cohabits only with real armored monsters (Pseudacanthicus, large Panaque, large Oscars) and never with conspecifics.
Aquarium Breeding: Very rare. The male digs a nest in the mud among the vegetation building a dome of foam and debris. The eggs are guarded and fiercely defended by the male until the yolk sac of the tiny predatory fry is reabsorbed.
Risks and Diseases: Has no scales. Does not tolerate copper-based drugs (they are lethal). The main risk is of a managerial nature: this colossus grows quickly and terrorizes or devours half of the aquarium inhabitants before the unsuspecting beginner realizes it.
Origem e distribuição geográfica
Omnipresent in the Amazon and Orinoco basin. Nocturnal predator of shady swamps, flooded forests (Igapó) and trickles saturated with decomposed vegetation. Capable of surviving in stagnant waters almost devoid of oxygen.
Origem
Amazônia, Orinoco e Guianas
Perfil de peixe
- Temperamento
- Semi-aggressive
- The Banded Knifefish is a highly intelligent, nocturnal predator with a notoriously aggressive and territorial temperament toward its own kind. Toward humans, they are often shy initially but can become surprisingly tame, sometimes learning to accept food directly from tongs or fingers. They possess a weak electric organ which they use for electrolocation to navigate and hunt in total darkness. They are completely intolerant of other knifefish and will actively hunt any fish small enough to fit in their mouths. Providing them with a secure, dark hiding spot is crucial to preventing daytime stress.
- Dieta
- Omnivore
- As nocturnal carnivores, their natural diet consists of small fish, worms, crustaceans, and various aquatic insects. In the home aquarium, they should be offered a hearty diet of meaty foods such as earthworms, chopped prawn, mussels, and pieces of fish fillet. While they may initially require live foods to trigger their feeding response, they can usually be weaned onto frozen or prepared sinking carnivore pellets. They rely heavily on their electric organ to locate prey in the dark, making them incredibly efficient hunters at night. Providing a varied diet ensures they receive necessary nutrients and remain healthy.
- Expectativa de vida
- 12-15 years
- Tamanho adulto
- 60 cm
- Proporção sexual
- Solitary
- Due to their extreme intolerance of their own kind, it is universally recommended to keep only a single Banded Knifefish per aquarium. Sexing them visually is extremely difficult, as there is no obvious sexual dimorphism outside of the breeding season when females may appear slightly plumper. Attempting to keep multiple individuals or establishing a specific sex ratio will almost certainly result in severe territorial battles and likely death. They use their electrical pulses not just for navigation, but for communication and aggression. Therefore, a solitary life is best for their health and safety.
- Frequência de alimentação
- Twice daily
- Adult Banded Knifefish should be fed once a day, preferably just before or after the aquarium lights are turned off, to mimic their natural nocturnal feeding habits. Because of their large size and predatory nature, they consume substantial meals, but overfeeding must be avoided to maintain water quality. Juvenile specimens can be fed twice a day with smaller portions to support their rapid growth rate. It is important to monitor their feeding, as they may outcompete slower bottom-dwellers for food at night. Any uneaten food should be removed the following morning.
- Carga biológica
- High
- The Banded Knifefish produces a moderate to heavy bioload due to its large adult size and carnivorous, predatory diet. They are enthusiastic eaters that generate substantial amounts of physical and chemical waste in the aquarium environment. A powerful, highly efficient filtration system, preferably a large canister filter, is essential to keep the water parameters within safe limits. Because they are messy eaters, uneaten food can quickly foul the water, making regular vacuuming of the substrate necessary. Consistent, large-volume water changes are critical to prevent the accumulation of nitrates, which can stress this species.
- Fluxo
- Stagnant
- They originate from slow-moving rivers, swamps, and flooded forests in South America, so they prefer gentle to moderate water flow. High-velocity currents should be strictly avoided, as it forces them to expend excessive energy to maintain their position and causes undue stress. A spray bar or a properly baffled filter outlet can provide the necessary circulation and oxygenation without creating turbulent conditions. They appreciate stagnant, heavily vegetated areas where they can rest completely undisturbed during the day. The flow should be just enough to keep detritus from accumulating on the substrate.
- Risco de salto
- Yes
- Like many elongate, muscular fish, they are capable of surprising bursts of speed and can easily jump out of the aquarium if startled. They are particularly prone to jumping when first introduced to a new environment or if pursued by an aggressive tank mate. A completely secure, tight-fitting lid with no large gaps is an absolute necessity to ensure they remain safely inside the tank. Floating plants can help diffuse light and provide a sense of overhead security, which may reduce their flight response. Keeping the tank in a quiet area also minimizes startle responses.
- Reprodução
- Oviparous
- Breeding the Banded Knifefish in a home aquarium is extremely rare and incredibly difficult to achieve due to their intense conspecific aggression. In the wild, they are known to build bubble nests among floating vegetation, where the male fiercely guards the eggs and fry. To trigger spawning, severe changes in water parameters simulating the wet season—such as massive water changes with cooler, softer water—are required. Given their intolerance of each other in confined spaces, pairing them without lethal consequences is a major hurdle. Consequently, most specimens available are wild-caught or bred in massive commercial ponds.
- Compatibilidade e companheiros de tanque
- Highly aggressive
- They are highly aggressive and territorial toward conspecifics and any other weakly electric fish; therefore, they should strictly be kept solitarily. While they ignore fish that are too large to swallow, they are nocturnal predators that will eagerly consume smaller tank mates while they sleep. Suitable companions include large, robust fish such as large cichlids, big doradid catfish, or large characins that occupy different water levels. They are known to have a nasty bite, so fin-nippers or overly curious fish should be avoided. Careful observation is required when introducing them to any community.
- Nível do tanque
- Middle/Bottom
- They are primarily bottom to mid-level dwellers that spend the daylight hours completely hidden away from the light. They require an aquarium with an abundance of hiding places, such as large PVC pipes, dense thickets of plants, and complex driftwood tangles. A soft, sandy substrate is recommended, as rough gravel can easily damage their scaleless, delicate skin as they forage. Once the lights go out, they become highly active, gracefully moving backward and forward through the water column using their elongated anal fin. Dim lighting or a dedicated moonlight phase will allow you to observe their nocturnal activities.
Modelos e parâmetros científicos
FishBase
Acesso aos dados científicos oficiais da espécie
FishBase v25.04Dados sincronizados em: 15/06/2026
- Nível trófico
- 3,6 ± 0,56 se
- Resiliência
- Média (1,4 - 4,4 anos)
- Tempo de geração
- 3,6 anos
- Unicidade filogenética (PD50)
- 0.5
- Relação bayesiana comprimento-peso
- a = 0.0038, b = 2.92
- VulnerabilidadeVulnerabilidade moderada (37 / 100)
Espécies relacionadas
Recomendações agrupadas por parentes próximos, escolhas de acompanhantes e cuidados semelhantes.
