Scientific Name: Polypterus ansorgii (Boulenger, 1910)
Maximum Size and Lifespan:
Polypterus ansorgii, commonly known as the Ansorgii Bichir, can reach up to 30–36 inches (75–90 cm) in length, making it one of the largest bichir species. In captivity, it can live 15–20 years or more with proper care and stable conditions.
Recommended Aquarium Size, Water Changes, and Care:
Due to its impressive size and active, predatory nature, a minimum aquarium size of 180 gallons (680 liters) is recommended for adult specimens. The tank should have a tight-fitting lid (bichirs are skilled jumpers) and ample bottom space with driftwood, rocks, and caves to mimic its natural environment. Substrate should be fine sand or smooth gravel to prevent injury.
Maintain water temperature between 76–82°F (24–28°C)
pH of 6.5–7.5
Strong filtration is necessary, but flow should be gentle as bichirs prefer calmer waters. Perform 25–30% weekly water changes to keep nitrate levels low and maintain optimal water quality.
Tankmates:
The Ansorgii Bichir is semi-aggressive and predatory but generally tolerant of similar-sized tankmates. Suitable companions include large, robust species such as:
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Other large Polypterus species
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Arowanas (of similar size)
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Datnoids
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Large Cichlids (e.g., Oscars, Peacock Bass, or Severums)
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Giant Gouramis or large Catfish species (e.g., Synodontis, Pimelodus)
Avoid small or slender fish that can fit into the bichir’s mouth, as they will be eaten.
Diet:
In the wild, P. ansorgii is a carnivorous predator feeding on smaller fish, crustaceans, and insects. In captivity, it accepts a wide variety of meaty foods, including:
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Earthworms, shrimp, krill, and silversides
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Chopped fish or shellfish
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Quality carnivore pellets or frozen foods
Feeding should occur 2–3 times per week for adults, with juveniles fed more frequently. Avoid fatty feeder fish to prevent health issues.
Overview:
The Ansorgii Bichir is a striking and ancient fish species known for its heavy armor-like scales, elongated body, and prehistoric appearance. It is powerful, intelligent, and relatively hardy once established. Due to its size and predatory instincts, it is best suited for experienced aquarists with large aquaria and strong filtration systems.
Natural Environment:
Polypterus ansorgii is native to West Africa, primarily found in Nigeria and Cameroon, inhabiting slow-moving rivers, swamps, and floodplains with soft, muddy bottoms and abundant vegetation. These waters are typically warm, slightly acidic, and rich in organic matter. The species uses its modified swim bladder to breathe atmospheric air, allowing it to survive in low-oxygen environments.
Breeding:
Breeding P. ansorgii in captivity is extremely rare and challenging. In the wild, spawning likely occurs during the rainy season. Males display more elongated anal fins and are slimmer, while females are fuller-bodied. Courtship involves the male wrapping his anal fin around the female to collect and fertilize eggs. Eggs are scattered among plants or substrate and left to hatch without parental care. In aquariums, successful spawning typically requires environmental triggers such as seasonal water changes, diet variation, and large, well-conditioned pairs.
