Knifefish, with their distinctive body shape and unique swimming style, are captivating additions to any freshwater aquarium. Among these, the Black Ghost Knifefish (Apteronotus albifrons) stands out as a popular choice. However, their specialized feeding habits require careful consideration. This article delves into the dietary needs of the Black Ghost Knifefish, providing a comprehensive guide for aquarists of all levels.
Knifefish Overview
Knifefish are broadly classified into two groups. The larger group, belonging to the Order Gymnotiformes, originates from Central and South America and includes ghost, banded, and glass knifefish. The smaller group, in the Family Notopteridae, is native to Southeast Asia and Africa and includes featherfin, African, and clown knifefish. A notable feature of most knifefish is their ability to generate and receive electrical discharges, which they use for navigation, communication, and locating prey.
Black Ghost Knifefish have weak eyesight. They rely on a built-in electric field to locate food and surrounding areas.
General Feeding Habits of Knifefish
Most knifefish are specialized feeders. Many species forage the bottom at night in search of crustaceans, worms, insects, and small fish. Clown, African, and featherfin knifefish are active predators and will readily consume any fish that fits in their mouths.
Dietary Needs of the Black Ghost Knifefish
The majority of knifefish are specialized feeders, with a number of species foraging the bottom at night in search of crustaceans, worms, insects, and small fish. Black Ghost Knifefish (BGK) are primarily carnivorous and not too difficult to feed.
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Recommended Foods
Live and Frozen Foods:
- Bloodworms: A favorite among BGK owners.
- Brine Shrimp: Suitable for smaller BGKs.
- Red Wigglers: Another option for larger BGKs.
- Market Shrimp: Tiny pieces of market shrimp can be offered.
- Ghost Shrimp
Pellets:
- Sinking Shrimp Pellets
- Aqueon Tropical Granules: A good choice for small to medium-sized knifefish.
- Cichlid Pellets: Another suitable option for small to medium-sized knifefish.
- Monster Fish Medley: Can be fed to larger species.
Feeding Strategies
- Nocturnal Feeding: Since most knifefish are nocturnal, small amounts of food can be fed after the aquarium light is turned off.
- Variety: Rotate their diet daily for best results.
- Quantity: Feed only what they can consume in 2 to 3 minutes, once or twice a day.
- Removal of Uneaten Food: Remove any uneaten food in the morning to avoid water quality problems.
- Training to Pellets: Try to adapt knifefish to pellet and other dry foods as soon as possible. Avoid the use of feeder goldfish or livebearers as they may carry diseases and are not nutritionally suitable. Try not feeding anything else if you want to get them on pellets. Generally not a hard fish to pellet train. I've seen entire tanks of them pellet trained. Even eating flake.
Foods to Avoid
- Feeder Goldfish and Livebearers: Avoid these as they may carry diseases and are not nutritionally suitable.
- Flake Food: Flake food may not be nutritionally dense enough for knifefish in the long run, especially since it is easy for them to get outcompeted for food by other fish.
Setting Up the Ideal Environment
Aquarium Size
Since some knifefish grow to be relatively large and most live long lives, appropriate plans should be made when purchasing them.
- Minimum Tank Size: A 55-gallon aquarium might be okay for the first year, but it is too small for the long term. A 75-gallon fish tank is the next upgrade that may last for a few more years. Ultimately, it is recommended getting a 120- or 180-gallon aquarium for an adult black knife fish.
- Large Knives: Ghost knives, featherfin knives, and African knives attain lengths of 8" to 12", requiring an aquarium of at least 55 gallons when full grown. Banded knives require at least 100 gallons, and adult clown knives will require a 200-gallon aquarium or larger.
- Unsuitable Species: Aba Aba knives reach lengths of over 5' in the wild and are not suitable for home aquarists.
Habitat and Decor
- Cover: Provide plenty of cover in the form of tall plants and driftwood, as well as caves and grottos, to help knifefish feel safe. Ample open areas for swimming should also be present.
- Plants: Ghost knives are well-suited to live in planted aquariums due to their calm, peaceful nature. When keeping large knives, use artificial plants with weighted bases to prevent them from being uprooted.
- Lighting: Lighting should be subdued to encourage them to come out during the day.
- Security: A secure cover should be used to keep them from jumping out of the aquarium.
Water Quality
Knifefish are scaleless and extremely sensitive to poor water conditions.
- Water Quality: Water quality should be pristine, with undetectable ammonia and nitrites, and nitrates below 20 ppm.
- pH: pH should be between 7.0 and 8.0.
- Alkalinity: Alkalinity should be between 5° and 10° (90 ppm to 180 ppm).
- Temperature: Temperature should be maintained between 75° and 80° F. If the aquarium is kept in rooms below 75°, use an Aqueon Aquarium Heater to maintain the correct temperature.
- Medication Sensitivity: Knifefish are sensitive to many medications, so the use of a UV sterilizer is recommended to prevent disease rather than having to resort to chemicals after a disease outbreak.
- Maintenance: Maintain good filtration and change 10% of the water every week or 25% every 2 weeks using an Aqueon Aquarium Water Changer or Siphon Vacuum Gravel Cleaner. Do not forget to treat tap water with Aqueon Water Conditioner before refilling your aquarium!
Behavior and Compatibility
Most knifefish are nocturnal and tend to be shy, especially when first introduced to an aquarium. As they settle into their new homes, they often become more outgoing during daylight hours, particularly around feeding time. They tend to be territorial and can be aggressive toward each other or closely related species, so they are best kept one to an aquarium with other peaceful fish that are too large to be eaten. This is especially important with clown knives, which not only get extremely large but are highly predatory.
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Compatible Tank Mates
Depending on the species of knifefish you keep, a few compatible fish include silver dollars, tinfoil barbs, angelfish, large cichlids, larger Gouramis, and Synodontis catfish. Always consult an aquarium expert before buying any new fish for your aquarium.
Tank Mates to Avoid
You don’t want any tank mates bullying or outcompeting them for food, such as aggressive cichlids or fast rainbowfish. We don’t recommend it since problems tend to arise. Knifefish are territorial and don’t like sharing their space with other electric fish, such as baby whale fish, elephant nose fish, and other knifefish.
Training and Interaction
A well-trained Ghost will rush to meet you when you put your hand in its tank. It will eat from your hand and even lay on it. The Ghost can be a truly friendly and playful creature. But in order to bring out the best in our Ghosts, we need to carefully design their environment. We need to condition their behaviour. We need to earn their trust. If any of these aspects is missed, we will end up with an introvert Ghost who stays in perpetual hiding.
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