Home / Fishes / Bichirs and ropefish / Mottled bichir
No federal permit to keepMottled bichir
Polypterus weeksii
Fishes › Bichirs and ropefish (Polypteriformes) › Polypteridae (Bichirs and ropefish)
Polypterus weeksii, the mottled bichir, is a fish in the family Polypteridae found in the central basin of the Congo River.
Care at a glance
Species-specific aquarium care
- Tank: At least 84 in long and 42 in front to back for one adult (adults commonly reach about 21.3 in / 54 cm).
- Water: Freshwater.
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 59 × 24 in (roughly 143 US gallons); space needed is rated “very large tank”.
- Difficulty: Not enough data to rate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Floor space is more important than depth with this species.”
- Tankmates: “Not to be trusted with tankmates it can fit in its mouth but is relatively peaceful otherwise.”
- Breeding: “Not recorded in captivity but is thought to breed in a similar way to other Polypterus species.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Bichirs and ropefish
Applies to most species in this group. Habitat: These African freshwater bottom predators use rivers and vegetated shallow waters, with ropefish especially associated with dense vegetation (rope, setup). Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- Small bichirs such as P. senegalus: published minimum footprint 122 × 38 cm; small/medium groups: 153 × 46 cm (setup).
- Large P. ornatipinnis, endlicherii and bichir: published starting footprint 183 × 61 cm; assess the actual adult size and stocking (setup).
- Adult ropefish: Seriously Fish specifies 150 × 60 × 60 cm, approximately 540 L (rope).
- Use heavy, tight lids, seal cable gaps, and leave an air gap with unobstructed surface access (setup, rope).
- Provide soft sand, wood/cave refuges and subdued lighting (setup).
- Provide ample biological filtration and protect heaters from physical damage (setup).
Climate & lighting
| Water | 77–82.4°F |
Diet
- Earthworms (rope).
- Prawns and mussel meat (rope).
- Bloodworms for appropriately sized specimens (rope).
Social life
- Avoid swallowable companions; ropefish can live in groups but lose food to vigorous feeders (rope).
Health watch
- Ammonia toxicity from inadequate biofiltration (fish_health).
- Parasitic skin and gill infections (fish_health).
- Nutritional deficiencies from unsuitable diets (fish_health).
Understanding the animal
About this animal
About this animal
It grows to about 54 cm in head-to-tail length. Named in honor of John Henry Weeks (1861-1924), Baptist missionary, ethnographer, explorer and diarist, who collected type at his mission station in Monsembe, upper Congo River, Zaire (now Democratic Republic of the Congo).
Quoted from the Wikipedia article “Polypterus weeksii” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater. Stays near the bottom. |
| Water it lives in | Freshwater. |
| Climate | Tropical climate. |
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 88°F (up to 90°F in the hottest sampled areas) |
| Cool-season lows | about 66°F (down to 62°F in the coldest sampled areas) |
| Average temperature | 76–78°F across sampled records |
| Relative humidity | 78–83% on average (driest month about 75%) |
| Rainfall | about 1686 mm a year |
Measured at 29 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | Polypterus weeksii, the mottled bichir, is a fish in the family Polypteridae found in the central basin of the Congo River. It grows to about 54 cm in head-to-tail length. Named in honor of John Henry Weeks (1861-1924), Baptist missionary, ethnographer, explorer and diarist, who collected type at his mission station in Monsembe, upper Congo River, Zaire (now Democratic Republic of the Congo). — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 59 × 24 in (about 143 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Sean Evans: Tank Setup for Bichirs and Ropefish Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Erpetoichthys calabaricus Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Management of Aquarium Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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