Black ghost knifefish care
Apteronotus albifrons · Amazon and Paraná basins
Black ghost knifefish swim forwards and backwards by rippling one long fin and find food with a weak electric field.
- Tank size
- 125 US gal or larger
- Temperature
- 73 to 82 °F (23 to 28 °C)
- Group size
- Alone or in a pair
- Temperament
- Semi-aggressive
- Adult size
- 20 in
- pH
- 6 to 7.5
- Hardness (GH)
- 2 to 12 dGH
- Lifespan
- 10 to 15 years
- Diet
- Carnivore
- Care level
- Demanding
In a 125 gallon
72½ × 18½ × 23⅛ in outsideHow to keep black ghost knifefish
Black ghost knifefish swim forwards and backwards by rippling one long fin and find food with a weak electric field. They grow to about 20 inches, so plan a 125 gallon or larger tank with tubes or caves to hide in by day and pristine water.
Diet: Carnivore: frozen bloodworm, brine shrimp, small worms. Fish food types compared · how often to feed.
Where they swim: Bottom of the tank.
Black ghost knifefish tank mates
Share the temperature and water, and neither side eats, nips or bullies the other. Check the full group in the stocking checker.
Bala shark
14 in · 125+ gal · 72–82 °F
Tinfoil barb
14 in · 150+ gal · 72–77 °F
Kissing gourami
12 in · 75+ gal · 72–82 °F
Uaru
9.8 in · 75+ gal · 79–86 °F
Blood parrot cichlid
8 in · 55+ gal · 76–80 °F
Severum
8 in · 55+ gal · 75–84 °F
Angelfish
6 in · 29+ gal · 76–84 °F
Giant danio
6 in · 55+ gal · 72–79 °F
Keep apart
Neon tetra: Adult black ghost knifefish eat fish under about 2 in; neon tetras grow to 1.6 in.
Cardinal tetra: Adult black ghost knifefish eat fish under about 2 in; cardinal tetras grow to 1.2 in.
Black neon tetra: Adult black ghost knifefish eat fish under about 2 in; black neon tetras grow to 1.5 in.
Green neon tetra: Adult black ghost knifefish eat fish under about 2 in; green neon tetras grow to 1 in.
Ember tetra: Adult black ghost knifefish eat fish under about 2 in; ember tetras grow to 1.2 in.
Glowlight tetra: Adult black ghost knifefish eat fish under about 2 in; glowlight tetras grow to 1.5 in.
What a black ghost knifefish tank needs
A tank of 125 US gallons or more (such as the 125 gallon) with a cover, and the equipment below.
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Aqueon QuietFlow Canister Filter 400
Rated by the maker for 100–150 US gal, which covers a 125 gallon black ghost knifefish tank without being built for a far bigger one.
EHEIM professionel 4+ 600 (2275)
Rated by the maker for 63–158 US gal, which covers a 125 gallon black ghost knifefish tank without being built for a far bigger one.
EHEIM thermocontrol 250
Black ghost knifefish need 73 to 82 °F; most homes run cooler, so a heater holds the temperature. Aqueon’s chart gives two 200 W heaters for a 125 gallon tank, and a second heater is worth having here: if one fails, the other keeps the water from going cold. Two Aqueon Pro 200 heaters, each rated by Aqueon for up to 75 gallons, make that pair. Heating a big tank.
API Freshwater Master Test Kit
Tests ammonia, nitrite, nitrate and pH, the readings that matter most before and after adding black ghost knifefish.
Seachem Prime 100 mL
Removes chlorine and chloramine from tap water at every water change.
Fluval Edge Thermometer
Shows the water temperature at a glance, so you know it stays within 73 to 82 °F.
We don’t list fish food: any good brand of the foods under Diet will do. Plan the whole tank's equipment →
Common black ghost knifefish problems
- Small tankmates such as neon tetras become food at night.
- They are sensitive to poor water and to some medications.
Test the water first whenever fish look unwell: see what your readings mean, then match the symptom. For disease, a vet who treats fish can diagnose it and advise treatment.
More to compare
Sources
Name, origin and adult size checked against Wikipedia: Apteronotus albifrons. Temperature, pH, hardness, group size, lifespan and minimum tank size are common hobby guidance, not figures from that article. Ranges are the range the species tolerates; aim for the middle. Minimum tank sizes are for an adult group. Drawings are our own; photo credits follow.
Photo credits
Real photographs from Wikimedia Commons, resized and cropped to fit; each is used under the license named.
- Black ghost knifefish Vassil, CC0, via Wikimedia Commons
- Bala shark H. Zell, CC BY-SA 3.0, via Wikimedia Commons
- Tinfoil barb Derek Ramsey (Ram-Man), CC BY-SA 2.5, via Wikimedia Commons
- Kissing gourami 5snake5, CC BY-SA 4.0, via Wikimedia Commons
- Uaru Brent Tibbats, CC BY 3.0, via Wikimedia Commons
- Blood parrot cichlid Citron, CC BY-SA 3.0, via Wikimedia Commons
- Severum Trisha M Shears, Public domain, via Wikimedia Commons
- Angelfish Citron, CC BY-SA 3.0, via Wikimedia Commons
- Giant danio Faucon, CC BY-SA 2.5, via Wikimedia Commons
- Neon tetra Holger Krisp, CC BY 3.0, via Wikimedia Commons
- Cardinal tetra CHUCAO, CC BY-SA 3.0, via Wikimedia Commons
- Black neon tetra Debivort, CC BY-SA 3.0, via Wikimedia Commons
- Green neon tetra Sascha Biedermann, CC BY-SA 2.5, via Wikimedia Commons
- Ember tetra Klaus Rudloff, CC BY-SA 4.0, via Wikimedia Commons
- Glowlight tetra gonzalovalenzuela; cropped by Kyknos, CC BY 2.0, via Wikimedia Commons
- Senegal bichir Zhyla at English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons
- Elephantnose fish Jutta234, CC BY-SA 3.0, via Wikimedia Commons
- African butterflyfish Toniher, CC BY-SA 3.0, via Wikimedia Commons
- Ropefish Michał Zalewski, CC BY-SA 3.0, via Wikimedia Commons
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