A prehistoric, heavily-armored predatory fish from the Congo River basin. Known for its distinctively large head, thick body, and prominent dorsal finlets. They possess functional lungs and must breathe atmospheric air. While peaceful toward fish too large to swallow, they are highly predatory and will consume anything that fits in their spacious mouths. They are notorious escape artists.
Weeksi Bichir At a Glance
Weeksi Bichir Tank Requirements
Will Weeksi Bichir fit in your tank?
Care guides tell you what Weeksi Bichir needs, the next question is whether your tank can safely provide it. Test Weeksi Bichir against your tank size, maintenance needs, and the fish you already keep before you buy.
Weeksi Bichir Water Parameters
Weeksi Bichir Temperament & Compatibility
Weeksi Bichir Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Adult / Standard
Full-grown adult. Requires a massive aquarium with a very secure, heavy lid. Must be kept with large tank mates (e.g., adult Oscars, large Silver Dollars, other large Bichirs).
Differs in 1 trait from base species
Also known as: Adult, Wild Caught
Juvenile (Grow-out)
Young specimen typically sold at 7-10cm. While they can be housed in smaller grow-out tanks temporarily, they have a fast initial growth rate and will quickly require an upgrade. Will eat small community fish.
Differs in 5 traits from base species
Also known as: Baby, Juvenile Bichir
Weeksi Bichir Care Guide Summary
The Weeksi Bichir, scientifically known as Polypterus weeksii, belongs to the Oddballs family group. Adults reach a maximum size of approximately 50 cm and have a eel body shape with a moderate growth rate. Classified as semi-aggressive, this species primarily occupies the bottom zone of the aquarium and produces a high level of biological waste.
To thrive, the Weeksi Bichir requires a freshwater only aquarium with a minimum volume of 470 litres and a tank length of at least 150 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 6–7.5 and a general hardness of 5–15 dGH. A low water flow is preferred.
Due to its specialist needs, the Weeksi Bichir is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 2 varieties: Adult / Standard and Juvenile (Grow-out). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Weeksi Bichir Habitat Setup
When setting up an aquarium for the Weeksi Bichir, a low water flow best suits their natural preferences. Because this species occupies the bottom zone, the aquarium layout should prioritise sufficient floor space with hiding spots among rocks, wood, or dense planting. Useful additions include a sand substrate to accommodate their sifting behaviour, smooth gravel or rounded substrate to protect their sensitive barbels, driftwood, which can serve as both a hiding place and a dietary supplement, and leaf litter or blackwater tannins to replicate their natural soft-water habitat. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Weeksi Bichir Compatibility Notes
Classified as semi-aggressive, the Weeksi Bichir is adaptable and can be kept singly or in a small group, offering flexibility when planning a community tank. When choosing tankmates, any fish small enough to fit in its mouth will likely be eaten and ornamental shrimp are not safe companions. Selecting tankmates that favour different water layers from the bottom zone can help reduce competition and territorial overlap.
Who Weeksi Bichir Is Actually For
Weeksi Bichir is best for a fishkeeper who wants a species that can settle into a calmer community setup and can provide someone who understands its individual space requirements. It makes the most sense for a hobbyist who will actually build around its needs, especially sand.
The most common mistake is treating Weeksi Bichir like any other community fish and skipping the soft sand it needs to forage safely. Another frequent problem is forcing it into an over-busy community when it would do better with more room or more deliberate tankmate choices.
Weeksi Bichir Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Weeksi Bichir.
Weeksi Bichir Feeding & Diet Considerations
The Weeksi Bichir is a predatory species that will readily consume small fish, so nano or bite-sized tankmates should be avoided, will hunt and eat ornamental shrimp, making it unsuitable for shrimp-focused setups, will eat fry, so breeding efforts in the same tank are unlikely to succeed, and is primarily active at dusk and dawn, so offering food shortly after lights-off ensures it receives adequate nutrition.
Frequently Asked Questions About Weeksi Bichir
How big does Weeksi Bichir get?
Weeksi Bichir (Polypterus weeksii) typically reaches a maximum adult size of approximately 50 cm. They have a eel body shape and a moderate growth rate.
What tank size does Weeksi Bichir need?
A minimum aquarium volume of 470 litres and a tank length of at least 150 cm are recommended for Weeksi Bichir. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Weeksi Bichir need?
Weeksi Bichir thrives in freshwater only conditions with a temperature range of 24–28°C, a pH between 6 and 7.5, and a general hardness of 5–15 dGH. A low water flow is preferred.
Is Weeksi Bichir peaceful or aggressive?
Weeksi Bichir is classified as semi-aggressive with an aggression score of 6 out of 10. They can work in community setups but may clash with certain tankmates.
Can Weeksi Bichir live alone?
Yes, Weeksi Bichir can be kept singly or in a group. They are flexible and adapt well to both setups.
Is Weeksi Bichir safe with shrimp?
No. Weeksi Bichir is known to eat ornamental shrimp and is not recommended for shrimp tanks. Even larger shrimp species like Amano Shrimp may be at risk.
Does Weeksi Bichir have any special tank requirements?
Yes. Weeksi Bichir benefits from sand (sifters), smooth gravel (sensitive barbels), driftwood (digestion/hiding), and leaf litter/blackwater in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Weeksi Bichir need a lid on the tank?
Yes. Weeksi Bichir is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Useful setup supplies
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- May 11, 2026
- Last updated
- May 11, 2026
- Issues or corrections?
- Contact the editorial team
Plants That Suit Weeksi Bichir
These plants pair well with Weeksi Bichir based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Amazon Frogbit
Limnobium laevigatum
Asian Watergrass
Hygroryza aristata
Asian Watermoss
Salvinia cucullata
Banana Plant
Nymphoides aquatica
Beckett's Water Trumpet
Cryptocoryne beckettii
Broad-leaved Crypt
Cryptocoryne pontederiifolia
Fish Similar to Weeksi Bichir
Delhezi Bichir (Armored Bichir)
Polypterus delhezi
An ancient, air-breathing predatory fish from the Congo River basin. Known for its distinct black vertical bands and dinosaur-like dorsal finlets. They are bottom-dwelling ambush predators with poor eyesight but an excellent sense of smell. While generally peaceful with similarly sized or larger fish, they are opportunistic piscivores and will eat anything that fits into their surprisingly large mouths.
Congo Bichir
Polypterus endlicheri congicus
The Congo Bichir is a prehistoric-looking, bottom-dwelling monster fish and one of the largest species in the Polypteridae family. They are obligate air-breathers and ambush predators that will eagerly consume any tankmate small enough to fit in their surprisingly large mouths. Due to their massive adult size, they require extremely large custom aquariums, heavy filtration, and a tight-fitting lid to prevent escapes.
Saddled Bichir
Polypterus endlicheri
A massive, prehistoric-looking predatory fish native to Africa. Known for its prominent dorsal finlets, striking 'saddled' striping, and ability to breathe atmospheric air using a modified swim bladder. They are bottom-dwelling ambush predators. They are completely peaceful to fish too large to swallow, but highly predatory toward anything else. They must be kept on soft sand, as they swallow their prey whole and ingested gravel can be fatal.
Polypterus Bichir Lapradei
Polypterus bichir lapradei
The Lapradei Bichir is a massive, ancient, air-breathing predatory fish native to West Africa. Featuring distinct dorsal finlets and a heavily armored, snake-like body, it is a fascinating 'monster fish'. As nocturnal ambush predators, they will consume any tank mate that fits in their surprisingly large mouths. However, they are remarkably peaceful with robust companions that are too large to eat. A tight-fitting lid is absolutely mandatory as they are notorious escape artists.
Marbled Bichir
Polypterus polli
An ancient, prehistoric-looking 'upper-jaw' bichir native to the Congo River basin. They are fascinating bottom-dwelling predators with paired lungs, requiring access to the water's surface to breathe atmospheric air. While generally peaceful towards tank mates too large to swallow, they are highly opportunistic nocturnal predators. A tight-fitting lid is mandatory, and fine sand substrate is critical to prevent fatal impaction during their lunging feeding behavior.
Senegal Bichir
Polypterus senegalus
A fascinating, prehistoric-looking predatory fish often called the 'Dinosaur Eel'. They possess a modified swim bladder acting as a lung and must have access to the surface to breathe. Though peaceful with large, deep-bodied tank mates, they are strictly carnivorous and will consume any fish or invertebrate that fits in their mouths. Excellent escape artists; a heavy, tight-fitting lid is mandatory.