Maximum Size and Lifespan:
Polypterus weeksii, commonly known as the Weeks Bichir or Mottled Bichir, can reach a maximum length of around 20–22 inches (50–55 cm) in captivity, though wild specimens may grow slightly larger. With proper care, these fish can live 15–20 years or more, making them a long-term commitment for experienced aquarists.
Recommended Aquarium Size, Water Change, and Care:
A minimum tank size of 180 gallons (680 liters) is recommended for an adult Weeks Bichir due to its large size and active, bottom-oriented behavior. Juveniles can be kept in smaller quarters temporarily but will need upgrades as they grow. The tank should have a tight-fitting lid as this species is an excellent escape artist capable of breathing air.
Maintain stable water parameters with temperatures between 76–82°F (24–28°C), pH 6.2–7.6, and moderate hardness. Provide efficient filtration with moderate flow, and perform 25–35% water changes weekly to ensure optimal water quality. A soft, sandy substrate with plenty of driftwood, rocks, and shaded areas will help mimic their natural environment and provide comfort. Lighting should be subdued.
Tankmates:
Polypterus weeksii is generally peaceful toward similarly sized or larger tankmates but will eat anything small enough to fit in its mouth. Suitable companions include large cichlids (like Geophagus, Severum, or Oscars), medium to large catfish (Synodontis, Auchenoglanis), larger characins, and other bichirs of similar size and temperament. Avoid small fish, fin-nippers, or overly aggressive species.
Diet:
Weeks Bichirs are carnivorous ambush predators. In captivity, they thrive on a diet of meaty foods such as earthworms, shrimp, fish fillets, mussels, and sinking carnivore pellets.
They also accept high-quality frozen foods like bloodworms, krill, and silversides. Feed 3–4 times weekly, adjusting portion sizes to avoid overfeeding.
Overview:
The Weeks Bichir is a striking, ancient fish known for its prehistoric appearance, mottled coloration, and calm demeanor. It’s a hardy, air-breathing predator with fascinating behaviors—often cruising the tank’s bottom or resting motionless under cover. This species is best suited to experienced aquarists capable of maintaining a large, stable, and well-structured aquarium.
Natural Environment:
Polypterus weeksii is native to the Congo River Basin in Central Africa, inhabiting slow-moving, swampy waters and floodplain regions with soft substrates and abundant vegetation. These environments are typically warm, dimly lit, and rich in detritus, providing shelter and hunting grounds for nocturnal predators like the Weeks Bichir.
Breeding:
Breeding Polypterus weeksii in captivity is extremely rare and not well documented. In nature, spawning likely occurs during the rainy season, when water levels and temperatures rise. Males display more elongated anal fins, which are used to fertilize the female’s eggs during courtship. Eggs are scattered among plants or substrate, with no parental care afterward. Successful breeding attempts in aquariums have been sporadic and typically require precise conditioning, seasonal simulation, and a spacious, heavily planted setup.
