How to take care of Black ghost knifefish?

We will talk about black ghost knifefish care in this blog post.We will also discuss important factors such as their habitat, types, lifespan, tank set-up, water parameters and healthcare, etc. Everything you need to know about black ghost knifefish care will be briefly discussed.


In this blog 

  • Key specifications of black ghost knifefish
  • Why is black ghost knifefish care important?
  • How many black ghost knifefish should you start with as a newcomer?
  • Habitat of black ghost knifefish
  • Types of black ghost knifefish
  • Different strains or colors of black ghost knifefish
  • General and physical attributes of black ghost knifefish
  • Black ghost knife fish lifespan
  • Black ghost knife fish tank set-up
  • Black ghost knife fish diet and feeding requirements
  • Black ghost knife fish healthcare and health conditions
  • Black ghost knife fish daily care and Bi-weekly care tips
  • Summary

How to take care of Black ghost knifefish?

Daily care tips for black ghost knife fish

  • Train them to feed them either in the evening hours or during night hours.So feeding should be once once a day.
  • Monitor and maintain all the vital parameters daily.
  • All the tank equipment and accessories should be in working conditions.If they are not working kindly replace them.
  • Water conditions should be monitored daily for nitrogenous waste product accumulation.

Bi-weekly care tips for black ghost knife fish

  • Partially change 30-50 % water weekly once.
  • Water testing should be done weekly religiously to keep the levels of ammonia and nitrate levels in check.
  • Qurantive live food for weeks before feeding them.
  • Clean tank filters , gravel siphons and other tank decorations weekly to avoid infections.kindly don’t use soaps and detergents to clean the tanks as it can be toxic to them.

Key specifications of Black ghost knife fish

Scientific name Apteronotus albifrons
HabitatConservation statusSouth america (tropical fish)Not listed
Lifespan10-15 years
Body sizeBody shapeColorSpecial traitSexual dimorphism20 inches (50 cm)Flat and elongatedWhite and blackElectrical organ at caudal peduncle Not clear
Another namesApteronotidae eelBlack knife
Optimum temperatureOptimum pHWater hardness73F-82F6.0-8.05-19 dGH (soft to hard)
TemperamentBeginner/experienced Semi-aggressive Experienced 
Care levelIntermediate 
Tank size and set-upTank type (Prefered)100-150 gallons Planted tank
Preferred plants/decorationsPlanted tanks /smooth substrate
CompatibilityOther peaceful fish
Number of black ghost knife fish species found There are a total 50 knife species found.
BreedingNot possible in aquarium settings

Why is black ghost knife fish care important?

Ghost knives are unique looking freshwater fish that are found in darker regions with lush vegetation.They need proper care in aquarium conditions because they don’t have scales on their body and are prone to infections due to poor water conditions.

It advised to give proper attention to the water conditions for their longevity in aquarium settings.

How many black ghost knife fish should you start with as a newcomer?

If you are a newcomer then please do proper research about them from the breeders or pet shop owners.They are quite large in size and need bigger tanks for their survival.

You cannot keep too many ghost knives in smaller size tanks.As a newcomer get 1 or 2 ghost knives and put them in bigger tanks.Get them from breeders who are aware of their genetics.

As a newcomer it will be a bit difficult to handle bigger tanks.So you need to think before buying a ghost knife fish for your tanks.

It is advised not to get wild caught black ghost knives as they carry potential parasites in their bodies which can infect other tank mates in a community tank.

Habitat of black ghost knife fish

  • Natural habitat- South America 
  • Tropical freshwater fish
  • Water movement – Slow 
  • Lush vegetation.

Types of black ghost knife fish

There are a total 50 knife species found till date.As such there is no data available on the types of black ghost knife fish at present.

Different strains or colors of black ghost knife fish

Black ghost knifefish are purely black with two white rings on its nose and one on the tail.There is just one albino morph variety of black ghost fish and that is white ghost knifefish.

General and physical attributes of black ghost knife fish

  • Body size- 20 inches, it’s their maximum size and they grow to this size in almost 2 years.
  • Body shape-They have this cone-like body, which is flat and elongated.
  • Poor eyesight and they communicate, hunt and navigate food through their electrical organ at the caudal peduncle.
  • Female black ghost knives emit higher frequency electrical signals than males and that is the only way to discriminate between male and female ghost knife fish.
  • Scaleless fish

Black ghost knife fish lifespan

Black ghost knife fish can live between 10-15 years and even more if their water parameters are stable and have a great diet and genetics. Their growth restricts in smaller tanks and poor water conditions.

Black ghost knife fish tank set-up

Tank sizeLight intensitySubstrateWater parametersTemperatureTank plantsTank mates

Tank size for black ghost knifefish

Tank size should be large and spacious i.e 100-150 gallons per ghost fish.Additional tank size should be 80 gallons per ghost fish.

Give them lots of hiding space to hide behind bushes and other caves works.This will keep them healthy and will give them the feeling of their natural habitat..

Light intensity for black ghost knifefish

Nocturnal fish- Very active during night.They live in dark areas in their natural habitat so low lighting like moon lighting system or subdued lighting is preferable in their aquarium.

Substrate /decorations for black ghost knifefish

Black ghost knifefish are bottom feeders so have a soft substrate in their tanks.

Soft sand and fine gravels should be the right choice and avoid coloured gravels because it can pollute the water chemistry and can give infections to ghost knives.

You can add smooth rocks,driftwoods,PVC pipes and caves for hiding.They are shy in nature and lots of hiding spots can make them feel safe and secure in the tanks.

It is advised to clean decorative items and gravel bottoms once a week to avoid contamination in the tanks.

Don’t use sharp and pointed decorative stuff in their tank.It can damage their body.

Water parameters for black ghost knifefish

  • Black ghost knifefish are sensitive to poor water conditions and prone to infections because they lack scales on their body.
  • Add them to a fully cycled tank without ammonia, nitrites and nitrates.
  • Water flow- It should be moderate like their natural habitat in the tank.
  • Water testing kits-A Good quality water testing kit is very important to keep the levels of nitrogenous waste products in check,because they get infections easily because they don’t have scales on their body.
  • Filters-Canister filters will keep the levels of ammonia and nitrates in check by filtering them out efficiently from the tanks.
  • UV sterilizers-Black ghost knife fish are scaleless and prone to infection and chemicals, so to avoid this you are advised to install a UV sterilizer in their tank.
  • Air pumps-They consume water from the oxygen,so proper oxygenation is must in their tanks.
  • Gravel siphon- Use this to clean gravels everyday to remove leftovers and other detritus from the tank.If not removed on time the uneaten food can spoil the water chemistry.

Temperature for black ghost knifefish 

The ideal temperature for ghost knives is between 73 F-82F and you need a thermometer to set the proper temperatures.Ghost knives will become inactive and stop eating if the temperature drops below 73F.

Sudden drops are not good for their health like other aquarium fish. Already they are without scales and are easily prone to infections due to poor water conditions. So it is important to maintain the water temperatures to avoid such mishaps.

Tank plants for black ghost knifefish

Ghost knives need dense vegetation like their natural habitat to conceal themselves during day time.Replicate their natural habitat to make them feel happy and healthy.They are purely carnivorous and won’t munch on plants.

  • Water wisteria 

Tank mates for black ghost knifefish

If you are planning to keep them in an established community aquarium then kindly pick peaceful fish of similar size,same temperament and same aquarium requirements.They don’t get along with small fish, slow swimmers and livebearers.

They get aggressive in overcrowded tanks so avoid accommodating too many tank mates in a tank of smaller size.Smaller tanks will restrict their natural growth and will make them more territorial towards other tank mates.

Suitable tank mates:

  • Corydoras (help to keep the tank clean)
  • Angelfish 
  • Large and peaceful cichlids
  • Discus 
  • Rope fish
  • Bichir 

Black ghost knife fish diet and feeding requirements

Carnivorous- Include protein, vitamin and mineral enriched balanced diets.They don’t like dry food.You can train them if you want to hand feed.Feeding them is a little tricky because they are very shy and take time to come out of their hiding spots to get their meals.

  • Live food- bloodworms, brine shrimps, tubifex
  • Frozen food- frozen prawns
  • Small pellets and flakes (least favorite, but can be trained to have )
  • Feeder fish
  • They don’t eat dry food, so don’t include that in their diets.

Feeding frequency:

  • Nocturnal in nature, so feed them either in evening or in night hours.
  • You can use automatic feeders too to feed them at that particular time.It is advised to train them to eat at the same time either in evening or during night time.

Black ghost knife fish healthcare and health conditions

Skin flukes or ich infection or white spot disease- A parasitic infection which causes skin irritation in black ghost knives.

The only cure is to maintain the right temperature and in this case increase the temperatures to break the parasitic cycle.

They are sensitive to copper based medicines, so consult your vet before giving them.


  • Not recommended for beginners because they need bigger tanks and proper tank maintenance.Their feeding habits are also different due to their nocturnal nature.
  • Bigger and spacious tanks with lots of hiding spots and lush vegetation are well suited for their overall growth.
  • Feeding time table is important to feed them since they are nocturnal in nature.You are supposed to either train them or use automatic feeders to feed them on time.
  • Being scaleless they are prone to many infections so it’s very important to maintain pristine water conditions for their longer lifespan.

Frequently asked questions on black ghost knife fish care

Can black ghost knife fish tolerate brackish water conditions?

Black ghost knife fish are tropical freshwater fish and they cannot survive in brackish condition.

Are ghost knife fish aggressive in nature?

They are not aggressive but can get aggressive in smaller size overcrowded tanks and with aggressive tank mates.