Bichir Care: Juveniles Mislead, Adults Need Real Floor Space
Bichirs are hardy in some ways, but they are not a casual community addition and often outgrow the tank many owners planned.
Bichir purchase reality check
Care area
| Care area | What beginners notice | What actually matters long-term | Takeaway |
|---|---|---|---|
| Size | Young fish look manageable | Adult body length and girth demand much more room | Buy for the adult, not the juvenile |
| Behavior | Often calm by day | Predatory at feeding time and nocturnal in habits | Do not trust tiny tankmates |
| Breathing | Surfacing can worry new keepers | Many bichirs routinely gulp air | Know normal behavior before panicking |
| Decor | Looks fine in a decorated tank | Needs open bottom areas and safe hiding spots | Balance cover with floor space |
Bichir keeper rules
| Secure every lid opening and cable gap | |
| Plan tankmates too large to be swallowed | |
| Provide open bottom territory plus sturdy shelters | |
| Keep filtration strong without excessive blasting current | |
| Research the exact Polypterus species because adult sizes vary | |
| Assume a store juvenile will stay small | |
| Mix bichirs with shrimp or small tetra-sized fish | |
| Interpret every air gulp as immediate illness |
Bichirs reward keepers who like oddball predators and are willing to build the aquarium around them rather than squeezing them into a standard community plan.
The most common bichir mistake is not water chemistry—it is underestimating adult footprint and predatory compatibility.
Polypterus senegalus (Senegal Bichir) and related species are sold as juveniles at 4 to 6 inches and look manageable in a 30-gallon tank. They reach 12 to 18 inches in most species (up to 30 inches in Polypterus endlicherii) and are escape artists capable of crawling across wet floors using pectoral fins. Bichirs are primitive ray-finned fish with rudimentary lungs that breathe atmospheric air -- they can survive brief terrestrial excursions and will exit an uncovered tank. Understand the adult size and the lid requirement before purchase.
| Species | Adult Size | Min. Tank | Notes |
|---|---|---|---|
| P. senegalus (Senegal) | 12–14 in | 75 gal | Best beginner bichir; most available |
| P. ornatipinnis (Ornate) | 18–24 in | 120 gal | Spectacular patterning; intermediate |
| P. endlicherii (Saddled) | 24–30 in | 125+ gal | Largest kept; advanced fishkeepers only |
Species and adult sizes
The most commonly kept species and their adult sizes: Polypterus senegalus (Senegal Bichir): 12 to 14 inches. P. ornatipinnis (Ornate Bichir): 18 to 24 inches. P. endlicherii (Saddled Bichir): 24 to 30 inches. P. delhezi (Armored Bichir): 14 to 16 inches. P. palmas (Shortfin Bichir): 12 to 14 inches. Senegalus is the default beginner species due to its smaller adult size and relative hardiness. All Polypterus species share the same armored appearance, lobed pectoral fins, and dorsal fin series.
Tank requirements and the escape problem
Minimum tank for an adult Senegal Bichir: 75 gallons (4 feet of length). Larger species require proportionally larger tanks -- a P. endlicherii needs 125+ gallons as an adult. All bichir tanks must have secure lids with no gaps larger than 1/4 inch. Bichirs locate gaps by feel and push through them. They will escape tanks with lids that have power filter cutouts or CO2 tube holes -- cover all openings with foam or mesh. A bichir found on the floor is not necessarily dead; if the skin is still moist, return it to water and observe. They can survive 30 to 60 minutes on a wet floor in many cases.
Water parameters and tank setup
Bichirs tolerate a wide range of water parameters, which is part of their appeal as a robust species. Acceptable range: temperature 75 to 84 degrees Fahrenheit (82 to 84 preferred), pH 6.5 to 7.8, moderate hardness. They are not sensitive to moderate nitrate accumulation but benefit from weekly partial water changes of 25 to 30%. Substrate: soft sand or fine gravel that the bichir can partially bury itself in. Coarse gravel abrades the ventral surface. Bichirs are primarily nocturnal; provide caves, driftwood, or PVC pipes for daytime hiding.
Diet: predatory and requires whole prey
Bichirs are ambush predators with poor eyesight who locate prey primarily by smell. They readily accept: earthworms, blackworms, frozen bloodworms, frozen Mysis shrimp, and whole feeder shrimp. Large adults accept small fish as prey, which means tankmates smaller than the bichir's mouth will be eaten. Prepared sinking pellets (Hikari Carnivore, NLS community pellets) can be accepted if the bichir was trained to them as a juvenile, but many adults ignore prepared foods initially. Feed 3 to 4 times weekly; bichirs do not require daily feeding as adults.
Tankmate compatibility
Bichirs are generally peaceful with fish that are too large to eat and that do not fin-nip their dorsal fin series. Suitable tankmates: large cichlids (Oscars, Jack Dempseys, large cichlids of similar size), large catfish, large tetras. Inappropriate tankmates: small fish (will be eaten), fin-nippers (tiger barbs, nippy tetras -- will damage the delicate dorsal rays), and other predatory fish that compete for the same territory. Multiple Polypterus species can be housed together in large enough tanks, though size disparities lead to small individuals being eaten.
Sources: Bartsch I, Polypterus: The Dinosaur Fish; Moller P, freshwater Polypteridae care and taxonomy; African cichlid and primitive fish keeper databases; peer-reviewed Polypterus locomotion and lung biology from Standen EM et al., Nature.