Home / Fishes / Knifefish and electric eels / Black ghost knifefish
No federal permit to keepBlack ghost knifefish
Apteronotus albifrons
Fishes › Knifefish and electric eels (Gymnotiformes) › Apteronotidae (Ghost knifefish)
The black ghost knifefish (Apteronotus albifrons) is a tropical ornamental fish belonging to the ghost knifefish family (Apteronotidae).
Care at a glance
Species-specific values
Values researched for this exact species. Where they differ from the group guide below, follow these. Air, surface and water temperatures are listed separately, and each source is kept as published rather than averaged.
| Water temperature | 73–82 °F (23–28 °C) Seriously Fish aquarium recommendation; not a wild collection measurement. | 282 |
| Water pH | 6–8 pH Seriously Fish aquarium recommendation; not a wild collection measurement. | 282 |
| Water general hardness | 5–10 dGH Seriously Fish aquarium recommendation; not a wild collection measurement. | 282 |
| Maximum total length | 500 mm TL | 282 |
| Minimum tank dimensions | length: 180 cm; width: 60 cm; height: 60 cm Adult long-term housing; a small juvenile sales tank is insufficient. | 282 |
| Social needs | Usually one specimen in an ordinary aquarium; pairs may result in bullying. Groups need very large quarters and monitoring. | 282 |
Species-specific aquarium care
- Tank: At least 96 in long and 39 in front to back for one adult (adults commonly reach about 19.7 in / 50 cm).
- Water: Freshwater.
- Temperature: 73–82°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–19 dGH.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 71 × 24 in (roughly 171 US gallons); space needed is rated “very large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 73–82 °F, pH 6–8, 5–10 dGH.
- Behaviour: temperament fights its own; kept alone; suited to a community tank.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “The choice of decor itself isn't critical, although the fish does appreciate plenty of cover.”
- Diet: “A predator that feeds mainly on insects and worms in nature.”
- Tankmates: “Generally peaceful to the point of timidity, although larger specimens are likely to eat small fish.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Ghost knifefish
Applies to most species in this group. Habitat: Black ghost knifefish inhabit flowing South American streams and rivers over sand and enter flooded forests seasonally. [fg183-ghost]. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For an adult Apteronotus albifrons, use at least 180 × 60 × 60 cm (about 648 L).
- Provide enough front-to-back width for a stiff-bodied adult to turn.
- Provide shaded roots, large wood or other daytime shelters and soft sand.
- Use dim lighting or floating plants to diffuse light.
- Maintain efficient filtration, well-oxygenated water and rigorous maintenance; some current is preferable.
Climate & lighting
| Water | 73.4–82.4°F |
Diet
- Live or frozen insect-larva foods.
- Earthworms in suitable portions.
- Prawn pieces.
- Pelleted foods after successful training.
Social life
- Keep A. albifrons singly with peaceful fish too large to swallow. Two individuals may result in bullying and starvation; groups require exceptionally large systems.
Health watch
- Wasting when bullied individuals cannot feed.
- Gill injury associated with poor water quality.
- Skin parasites or secondary infections after introducing infected livestock; general aquarium-fish risks.
Understanding the animal
About this animal
About this animal
They originate in freshwater habitats in South America where they range from Venezuela to the Paraguay–Paraná River, including the Amazon Basin. They are popular in aquaria.
Quoted from the Wikipedia article “Black ghost knifefish” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater. Uses both the bottom and open water. Occurs in rapidly flowing waters of creeks with a sandy bottom. Is a micro-predator of insect larvae. |
| Water it lives in | Freshwater, 73–82 °F (23–28 °C), pH 6–8, hardness 5–19 dH. |
| Climate | Tropical climate. |
What this means for care
- Keep water within its wild range, 73–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 91°F (up to 94°F in the hottest sampled areas) |
| Cool-season lows | about 68°F (down to 55°F in the coldest sampled areas) |
| Average temperature | 74–81°F across sampled records |
| Relative humidity | 74–82% on average (driest month about 70%) |
| Rainfall | about 1929 mm a year |
Measured at 265 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The black ghost knifefish (Apteronotus albifrons) is a tropical ornamental fish belonging to the ghost knifefish family (Apteronotidae). They originate in freshwater habitats in South America where they range from Venezuela to the Paraguay–Paraná River, including the Amazon Basin. They are popular in aquaria. The fish is all black except for two white rings on its tail, and a white blaze on its nose, which can occasionally extend into a stripe down its back. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Wild diet | The black ghost knifefish is considered one of the large-mouthed species of the Apteronotidae family and has been observed eating other smaller fish and shrimp. They are carnivores and hunt during the night. Their diet mainly consists of insect larvae, small crustaceans, and smaller fish. — Wikipedia (community-edited) |
| Appearance and size | The black ghost knifefish has an elongate compressed body with a finless back, short snout, large mouth and a long fin along its abdomen. This fin is a long fused ventral and anal fin as these fish typically have an absent caudal fin. Adults can reach mature lengths of 45-50. — Wikipedia (community-edited) |
| Biology | Occurs in rapidly flowing waters of creeks with a sandy bottom. Is a micro-predator of insect larvae. Possesses a weakly discharging neurogenic electric organ and ampullary electro receptors that are distributed from head to tail (; 10841). — FishBase |
| History and naming | In regards to reproduction, members of the gymnotiform order are fractional spawners, so the black ghost knifefish spawn their sticky eggs irregularly, as the number of eggs spawned is not consistent every time. Their fecundity can range from 1 to 105 eggs. They also choose spawning sites carefully to ensure well-hidden eggs. — Wikipedia (community-edited) |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Maximum recorded lifespan
Longest recorded lifespan reported by each database; typical lifespans are usually shorter.
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 71 × 24 in (about 171 US gallons).
Veterinary & husbandry research
Veterinary & husbandry research
- Diagnosis and Off-Label Treatment of Subcutaneous Putative Dracunculoid Nematodes in Apteronotus albifrons Originating From Wild-Caught Fisheries Cardoso PHM et al., Journal of fish diseases 2026
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish: Apteronotus albifrons Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Tropical Fish Hobbyist: Apteronotus albifrons Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.