Ghost Knifefish Care Sheet

Ghost Knife Fish

This care sheet covers the Ghost Knifefish species, including:  

  • Black
  • Golden
  • Brown
  • White
  • Clouded
  • Dusky

Characteristics

 

Care Difficulty Intermediate
Average Life Span Up to 15 years when properly cared for, depending on species
Average Adult Size Up to 18 inches long, depending on species
Diet Carnivore
Minimum Habitat Size          40 gallons for juveniles only
Water Temperature

73-80°F

Habitat

 

Habitat size

Keep in an appropriately sized aquarium for the species selected, which can range from 40 gallons for small juveniles up to a 100+ gallon aquarium for adults.


Building your habitat

  • Water health
    • Provide proper filtration to ensure optimal water quality to help maintain health; low to moderate water circulation should be provided to mimic the water currents and high oxygen levels found in the ghost knifefish’s natural habitat
    • Stable water quality (pH, ammonia, nitrate, nitrite) and water temperature are critical to the health of aquatic life; if you are unsure of your water quality, bring a sample to Petco for free testing
    • An aquatic heater should be utilized to stabilize water temperature, ensuring it does not fluctuate more than 2 degrees in either direction in a 24-hour period
    • Ghost knives will benefit from the addition of freshwater salt to the aquarium. Being a scaleless species be careful to not add too much salt. The specific gravity should be kept at 1.002; do not allow specific gravity to fluctuate more than 0.001 in either direction in a 24-hour period
  • Décor: Provide plenty of space for swimming, as well as plants, rocks, or décor for hiding places. Ghost knives are nocturnal and will need a cave to help feel secure during the day
  • A top should be added to the aquarium as they can jump out of the aquarium


Feeding


A well-balanced Ghost Knife diet consists of:

  • Brine shrimp, mysis shrimp, daphnia, bloodworms, tubifex (live, freeze-dried, or frozen) and are known to accept pelleted foods.

Things to remember when feeding your ghost knifefish:

  • Feed small amounts two to three times daily, no more than your fish will eat in 1–2 minutes
  • Thaw frozen food before feeding
  • They are nocturnal and food should be provided at night


Ghost Knifefish care

  • Maintaining great water quality with regular water changes and adequate filtration is important to help keep your ghost knife healthy
    • Daily: Check filter, water temperature and other equipment
    • Weekly: Test water quality at least once a week
    • Weekly to monthly: Change 10–25% of the total volume of water every 2–4 weeks, or as needed; change filter media monthly

  • Avoid overcrowded conditions, which are a major cause of stress and disease


Where to buy

Ghost Knifefish are available for purchase at Petco online and in-store; availability varies by location. If visiting your local Petco Pet Care Center location, please call ahead to check availability.

Ghost Knifefish supplies

  • Appropriately sized aquarium
  • Aquarium top
  • Appropriate food, freeze-dried and frozen
  • Décor
  • Water conditioner
  • Filter
  • Water test kit
  • Full-spectrum lighting
  • Net
  • Thermometer
  • Freshwater substrate
  • Heater
  • Refractometer
  • Airline tubing
  • Airstone
  • Air pump
  • Check valve
  • Freshwater salt
  • Live plants


Tank mates

Ghost Knives are generally peaceful and can be kept with many varieties of fish of similar or larger size and temperament. Ghost knives are territorial and don’t like sharing their space with other electric fish species like other ghost knives, elephant nose fish, and baby whales.

Health

Signs of a healthy fish

  • Clear eyes
  • Eats vigorously
  • Good coloration
  • Free of parasites or disease

Red flags (if you notice any of these signs, contact your local aquatic specialist or veterinarian)

  • Loss of color or appetite
  • Spots or fungus on body or mouth
  • Cloudy eyes or pop-eye
  • Listlessness
  • Labored breathing
  • Erratic swimming
  • Weight loss
  • Bloating
  • Frayed or discolored fins

Common Ghost Knifefish health issues

 

Health issue

Symptoms or causes

Suggested action

Fin rot

Frayed or disintegrating fins; the base of the fins usually reddens

Improve water quality; consult your local aquatic specialist or aquatic veterinarian for treatment.

Bacterial infections

Cloudy eyes, open sores and/or reddening of the skin

Improve water quality; add or slightly increase freshwater aquarium salt level; use a commercial antibacterial remedy, for scaleless fish, as directed; consult your local aquatic specialist or aquatic veterinarian for treatment

Ich

White spots appear on fins and body; fish rubs against hard objects or swims erratically, rapid respirations

Quarantine fish immediately; add or slightly increase freshwater aquarium salt level and use a commercial ich remedy, for scaleless fish, as directed; Consult your local aquatic specialist or aquatic veterinarian for treatment

Cottonmouth or Columnaris

Cottony white growths along the body and/or gills, frayed fins and gills turn brown and necrotic in late stages; caused by bacterial infection

Quarantine fish; improve water quality; lower aquarium temperature to 72°F to deter bacteria from growing; medicate as directed; consult your local aquatic specialist or aquatic veterinarian for treatment


FAQs

  • How long do ghost knifefish live? Ghost knives can live up to 15 years when properly cared for.
  • What do ghost knifefish eat? Ghost knives should be provided with a variety of freeze-dried, frozen, or live brine shrimp, mysis shrimp, daphnia, bloodworms, tubifex and pelleted foods.
  • What fish can live with ghost knifefish? Ghost knives are generally peaceful and can live with other appropriately sized and similar temperament fish like angel fish and peaceful South American cichlids. Ghost knives are territorial and don’t like sharing their space with other electric fish species like other ghost knives, elephant nose fish, and baby whales.
  • How big do ghost knifefish get? Ghost knives can grow up to 18”, depending on species.
  • Freshwater Angelfish Care Sheet
  • Central and South American Cichlid Care Sheet
  • Catfish Care Sheet


Notes and resources

Ask a Pet Care Center store employee about Petco's selection of products available for the care and happiness of your new pet. All products carry a 100% money-back guarantee.

Because all aquatic life are potential carriers of infectious diseases, such as atypical mycobacterium and salmonella, always wash your hands before and after handling your aquatic life and/or habitat contents to help prevent the potential spread of diseases.

Pregnant women, children under the age of 5, senior citizens and people with weakened immune systems should contact their physician before purchasing and/or caring for aquatic life and should consider not having aquatic life as a pet.

Go to the Centers for Disease Control at cdc.gov/healthypets for more information about aquatic life and disease.

The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, please contact your veterinarian as appropriate.

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