A bichir resting under driftwood can look like a living fossil, then launch across the tank the second food hits the water. That contrast is exactly why these Polypterus species are so addictive to keep. Knowing how to care for bichir means planning for more than a cool-looking juvenile: these are predatory, long-lived fish that need floor space, secure housing, clean water, and tank mates chosen with real care.
Whether you are drawn to a compact Senegal bichir or building a display around a large Endlicheri bichir, the goal is the same - create a stable aquarium where this bottom-oriented hunter can behave like a bichir.
Start With the Adult Size, Not the Store Size
Bichirs are often sold at a manageable few inches, but many quickly outgrow the tank that looked generous on day one. Their long bodies need room to turn, patrol, and settle on the bottom. Tank footprint matters more than extra height.
A 75-gallon aquarium can work well for one of the smaller commonly kept species, such as a Senegal bichir (Polypterus senegalus), which typically reaches around 12 to 14 inches. Delhezi and similar mid-sized species often deserve a 90-gallon or larger footprint. For ornate bichirs, Endlicheri bichirs, Congo bichirs, and other true heavyweights, think 125 gallons as a starting point and go larger whenever possible. A six-foot aquarium gives large bichirs far more usable territory than a tall but narrow tank.
Research the exact species before bringing one home. Common names get used loosely in the trade, while species such as Polypterus ornatipinnis, P. endlicheri, and P. congicus have very different adult potential. This is one area where scientific labeling protects both the fish and your future stocking plan.
How to Care for Bichir With the Right Setup
Bichirs are hardy only when their environment is sensible. They are not a substitute for cycling a tank, undersizing filtration, or ignoring water changes. Start with a fully established aquarium with zero ammonia and nitrite before the fish arrives.
Keep water temperatures around 75 to 82°F. A neutral to slightly soft water profile works for most species, with a pH roughly between 6.5 and 7.8. Stability matters more than chasing a perfect number. If your tap water is consistently within a safe range, regular maintenance is usually more valuable than constant chemical adjustment.
Use filtration that can handle a messy carnivore. A strong canister filter, sump, or a combination of mechanical and biological filters keeps waste from building up, but current should not turn the entire tank into a river. Bichirs appreciate areas of gentler flow where they can rest. Position returns so the surface still moves enough for healthy gas exchange.
The aquarium also needs a tight-fitting lid. Bichirs are capable escape artists, especially at night or when startled. Cover openings around filters, tubing, and cords. At the same time, do not seal off access to air. Bichirs possess primitive lungs and regularly rise to the surface to gulp air. Seeing this behavior is normal, not a sign that the fish is struggling.
For the bottom, fine sand is an excellent choice because bichirs spend so much time nosing around the substrate. Smooth, rounded gravel can also work. Avoid jagged rock, sharp decor, and rough gravel that can damage a fish's belly or fins. Add broad driftwood, caves, PVC shelters hidden by decor, and rock structures that are firmly secured. They do not need a bare tank, but every decoration should leave clear swimming lanes.
Feed Like a Predator, Not a Garbage Disposal
Bichirs have a strong appetite, and that can tempt owners to overfeed. A good diet is varied, protein-rich, and portioned for the fish's size and activity level. Quality sinking carnivore pellets should form the foundation for many captive bichirs, especially once they are trained to recognize them as food.
Supplement pellets with thawed frozen foods such as shrimp, krill, silversides in appropriate portions, mussel, clam, earthworms, and other meaty aquarium foods. Juveniles often eat more frequently, while established adults may do well with measured feedings several times per week. Watch body condition rather than feeding purely by schedule. A bichir should look solid and muscular, not pinched behind the head or bloated.
Avoid relying on feeder fish. They can introduce parasites and disease, and a steady diet of low-quality feeders is not balanced nutrition. Live foods may help a shy new bichir begin feeding, but they are better used as a temporary tool than a permanent menu.
Feed near dusk or after aquarium lights dim if your bichir is hesitant. Many become bold daytime eaters once settled, but their instincts are still strongest in lower light. Use feeding tongs for larger specimens when appropriate. It helps direct food to the bichir instead of letting faster tank mates take every bite.
Pick Tank Mates With a Predator's Mouth in Mind
The simplest bichir compatibility rule is blunt: if it fits in the bichir's mouth, it may eventually become food. Small tetras, juvenile livebearers, tiny loaches, dwarf shrimp, and undersized catfish are risky even if the bichir seems peaceful at first.
Good tank mates are usually peaceful to moderately assertive fish too large to swallow and too fast or sturdy to be bullied. Depending on the bichir species and aquarium size, possibilities may include larger rainbowfish, silver dollars, severums, geophagus, larger peaceful cichlids, certain plecos, and other appropriately sized oddballs. Large tanks give you more options because every fish can establish space.
Aggressive fish are a different problem. Fin-nipping cichlids can harass bichirs, while highly competitive predators may outfeed them or injure them. Do not assume a bichir is safe simply because it looks armored. Their long dorsal finlets and soft underside can be damaged by the wrong company.
Keeping multiple bichirs can be rewarding, especially in a large aquarium with several shelters, but size differences matter. Mixing a large individual with a small juvenile creates a potential meal-sized situation. Add similarly sized fish when possible, provide enough food, and monitor introductions closely.
Acclimation and Quarantine Matter
A new bichir may hide for several days, skip a meal, or stay motionless under cover. Give it a calm start. Dim the lights, avoid chasing it around with a net, and make sure its first hiding place is ready before it enters the aquarium.
Quarantine is especially smart for predatory fish headed into valuable display tanks. A separate, cycled quarantine setup allows you to observe appetite, check for external issues, and make sure the fish is stable before mixing it with established livestock. It also lets you train a stubborn juvenile onto prepared foods without competition.
When acclimating, match temperature carefully and avoid sudden swings in water chemistry. Net the fish into the new aquarium rather than adding shipping water to your system. Then leave the lights low and resist the urge to test its appetite every hour.
Keep the Water Clean Enough for a Big Appetite
Bichirs produce waste, and monster-fish style feeding can overwhelm an aquarium that looked clean yesterday. Test water regularly, particularly in a newer system or after increasing food amounts. Ammonia and nitrite must remain at zero. Nitrate should be managed through water changes, sensible stocking, plant growth where suitable, and effective filtration.
A weekly partial water change is a solid baseline, but the right amount depends on tank size, stocking level, feeding, and your nitrate readings. Vacuum open areas of substrate during maintenance, clean filter media in removed tank water, and never replace all biological media at once. The point is to export waste without disrupting the beneficial bacteria that keep the aquarium stable.
Watch your bichir during routine care. Clamped fins, rapid breathing, unexplained pale patches, refusal to eat after settling in, or repeated surface gasping combined with distress can signal a water-quality or health problem. One relaxed trip to the surface is normal. A fish struggling at the surface is not.
A well-kept bichir tank has a special presence: ancient fish moving through a modern display, calm for hours and suddenly electric at feeding time. Give your bichir space to grow, clean water to thrive in, and food worth hunting for, and it can become the fish everyone notices first.