Ossa Knifefish – Apteronotus ossa
The Ossa Knifefish is a fascinating and rare species prized by advanced aquarists for its unique shape, smooth movements, and striking appearance. With its elongated, laterally compressed body and undulating fin motion, this knifefish glides gracefully through the aquarium, making it a true showpiece.
Like many knifefish, the Ossa Knifefish is nocturnal and enjoys a dimly lit tank with plenty of hiding spaces. It is best suited for experienced fishkeepers with larger aquariums, as it can grow quite large and has specific care needs.
Key Details:
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Scientific Name: Apteronotus ossa
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Common Name: Ossa Knifefish
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Origin: South America (Amazon Basin)
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Size Purchased: 3" – 5"
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Adult Size: ~16" – 20"
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Type: Freshwater Knifefish
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Temperament: Semi-aggressive, predatory
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Tank Size: 100+ gallons
Water Parameters:
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Temperature: 75–82°F
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pH: 6.0–7.5
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Hardness: Soft to Moderate
Diet:
Carnivorous. Prefers live and frozen meaty foods such as bloodworms, blackworms, brine shrimp, and small fish. Will usually not accept dry prepared foods.
Care Notes:
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Provide ample hiding places with caves, driftwood, or PVC pipes.
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Keep lighting dim or subdued.
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Best housed alone or with large, peaceful tankmates (may prey on smaller fish).
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Not recommended for beginners due to size and feeding requirements.
Why Choose the Ossa Knifefish?
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Rare, exotic species perfect for advanced aquarists.
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Graceful swimming style and unique body shape make it a centerpiece fish.
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A true collector’s specimen for large freshwater aquariums.