Bichirs are African ray-finned fishes in the genus Polypterus. The “dinosaur eel” nickname does not make them true eels, and living bichirs are not the ancestors of amphibians. They are predators that need adult floor space, secure covers and unobstructed access to atmospheric air.
Identify the species before choosing the aquarium
Do not buy a fish labeled only “dinosaur bichir” and assume it stays a foot long. Body size differs greatly between species, and standard length excludes the tail. Growth also varies; a fixed monthly growth promise is not a housing plan.
Senegal bichir, P. senegalus: a relatively active and commonly sold species. The species profile recommends a 150 × 60 cm adult aquarium base and lists larger maximum sizes than many shop labels suggest.
Ornate bichir, P. ornatipinnis: a much larger fish, listed at about 60 cm standard length with a 180 × 60 cm adult footprint. A juvenile’s attractive pattern does not reduce its long-term needs.
Saddled bichir, P. endlicherii: another giant species. Its profile recommends a 210 × 120 cm base. Adding height to a narrow aquarium does not provide the same usable space.
The pictured P. delhezi is a different species again. Identify it separately rather than assigning every bichir one of the three footprints above. Multiple adults or other large bottom-dwellers require additional territory and feeding space.
Air access, cover and layout
Bichirs have lungs as well as gills. Research on polypterid breathing documents their use of spiracles to inhale air. Leave an air space beneath a secure, ventilated cover and keep their route to the surface clear. Oxygenated water does not justify denying surface access.
Close cable and pipe gaps: bichirs can escape through surprisingly small openings. Use smooth, stable refuges and appropriate substrate, avoid sharp edges, and leave open areas for movement. Plants can provide shade and cover but large fish may disturb them. Do not deliberately place a bichir on land to demonstrate its movement.
Water and filtration
Match conditions to the identified species and source stock. Many commonly kept bichirs suit stable tropical water around 24–27°C, but check the exact species rather than imposing one range on every fish. Measure pH and hardness before changing chemistry.
Complete the nitrogen cycle, maintain zero ammonia and nitrite, and provide effective biological filtration and surface movement. Test nitrate and remove accumulated debris during regular partial water changes. Air breathing does not make polluted water acceptable.
Feeding
Offer appropriately sized sinking foods intended for carnivorous fish, with varied suitable aquatic frozen or live foods. Check acceptance before relying on a pellet. Deliver food near the bichir’s resting area, often under dim light, and watch it swallow rather than assuming scraps reach the bottom.
Live feeder goldfish or other fish are unnecessary and may introduce infections. Avoid mammal and poultry meat as staples. Do not force-feed an otherwise healthy fish to train it; assess stress, water quality and competition if it refuses food.
Tank mates and breeding
Small fish and shrimp may be eaten, including at night. Large companions can still attack a bichir’s eyes or fins; scales do not make it immune. Piranhas and highly aggressive cichlids are poor default choices. See the bichir compatibility guide and maintain a separation option.
Breeding requires identified mature stock, ample space and prepared fry accommodation. Males commonly have broader anal fins, but maturity and development vary. Do not apply one age threshold or a sudden cold-water treatment to every species. Eggs and young require protection, appropriately sized food and close water-quality management; breeding is a separate project from routine adult care.
