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The bichir (pronounced BIH-cheer) is one of the most ancient-looking fish you can keep in a home aquarium. These African predators carry a row of sharp dorsal finlets instead of a single fin, and they breathe atmospheric air using a primitive pair of lungs. That last trait is what catches most new keepers off guard: a bichir that cannot reach the surface will drown. Beyond that single requirement, bichirs are surprisingly forgiving fish that reward patient keepers with lifespans of 15 years or more.
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Table of Contents
Quick Facts
| Common name | Bichir |
|---|---|
| Scientific name | Polypterus senegalus (Senegal bichir, most common); 12+ species in the genus |
| Origin | Africa (Nile basin, tropical West and Central Africa) |
| Adult size | 12–24 inches depending on species |
| Minimum tank size | 55 gallons (125+ gallons for larger species) |
| Temperature | 75–82°F (24–28°C) |
| pH | 6.5–7.5 |
| Hardness (GH) | 5–20 dGH |
| Lifespan | 15–20 years |
| Temperament | Semi-aggressive; peaceful with tank mates too large to swallow |
| Diet | Carnivore; meaty whole foods and sinking pellets |
| Care level | Intermediate |
Understanding the Bichir’s Air-Breathing Ability
Bichirs belong to the family Polypteridae, a group that split from other ray-finned fishes roughly 400 million years ago. Their most unusual feature is a pair of vascularised swim bladders that function as primitive lungs. In oxygen-poor African swamps, this lets bichirs survive conditions that would kill most other fish. In your tank, it means they will regularly swim to the surface to take a gulp of air. A tight-fitting lid is not optional: bichirs are skilled escape artists that can climb damp surfaces and will dry out on the floor.
New keepers sometimes mistake the air-gulping behaviour for a water quality problem. It is not. Even in perfectly clean water, a bichir will surface several times per hour. If you notice gasping at the surface combined with lethargy or clamped fins, check your water parameters first, but do not assume normal surfacing is a distress signal.
Appearance
Bichirs have an eel-like body covered in thick, rhomboid scales that look almost prehistoric. The defining feature is the series of 5–18 separate dorsal finlets that run from just behind the head to the base of the tail, each supported by a stiff spine. The pectoral fins are fleshy and leg-like, and bichirs use them to prop themselves on the substrate and to “walk” across the bottom. The Senegal bichir (the most widely available species) is a pale grey to olive colour with a cream underside. Ornate bichirs (Polypterus ornatipinnis) display bold black and yellow marbling. Delhezi bichirs show distinctive banded patterns.
Sexing bichirs requires a look at the anal fin. Males have a noticeably wider, thicker anal fin than females. This difference becomes reliable at around 2 years of age. In younger fish, sexing is difficult and often inaccurate.
Water Parameters
| Parameter | Acceptable range | Optimal |
|---|---|---|
| Temperature | 73–84°F (23–29°C) | 77–80°F (25–27°C) |
| pH | 6.0–8.0 | 6.8–7.2 |
| Hardness (GH) | 5–20 dGH | 8–15 dGH |
| Ammonia / Nitrite | 0 ppm | 0 ppm |
| Nitrate | <40 ppm | <20 ppm |
Bichirs are tolerant of a wide parameter range, which reflects their native habitat: slow, heavily vegetated floodplains and swamps where chemistry varies with rainfall and season. Most neutral to slightly alkaline tap water in the US and UK falls comfortably within their range. The one parameter that causes problems when it drifts is temperature. Sustained temperatures below 72°F slow digestion and suppress the immune system, making fish vulnerable to bacterial infections. Use a reliable heater with a separate thermometer to confirm accuracy rather than trusting the heater’s dial alone.
Weekly 25–30% water changes keep nitrates in check. Bichirs are messy eaters and heavy bioload producers, so strong biological filtration is essential. Run a canister filter rated for at least twice your tank volume, and rinse filter media in tank water (never tap water) during changes to preserve beneficial bacteria.
Tank Size and Setup
A 55-gallon tank is the minimum for a single Senegal bichir, but 75 gallons is a better starting point if budget allows. Larger bichir species like the ornate bichir reach 20 inches and need 125 gallons or more. The reason is simple: a bichir’s patrol range at the bottom of the tank is constant, and cramped conditions lead to stress and aggression toward tank mates. Larger tanks also dilute waste and maintain stable chemistry more easily, which matters at the long lifespans these fish achieve.
Setup principles:
- Substrate: Fine sand or smooth gravel. Bichirs rest on the bottom and can abrade their belly on coarse substrate over time. Sand is preferred.
- Hiding places: PVC pipe sections, large smooth rocks, or driftwood caves. Bichirs are more active and calmer when they have retreats to rest in during the day.
- Planting: Sturdy plants like Java fern or Anubias attached to wood or rock. Avoid fine-leaved plants that bichirs will uproot.
- Flow: Low to moderate. Bichirs come from still to slow-moving water and do not appreciate strong currents.
- Lid: Tight-fitting, with no gaps. Even a 1-inch gap is a bichir-sized exit.
Tank Mates
Bichirs are opportunistic predators: if a tank mate fits in their mouth, it is a meal. The rule of thumb is to keep bichirs only with fish that are at least as long as the bichir’s head. Despite this, bichirs generally ignore fish they cannot swallow and coexist well in mixed predator tanks.
Avoid: Small schooling fish (neon tetras, guppies, endlers), small shrimp, small bottom dwellers, and anything that can easily fit in the bichir’s mouth at its current size (remember they grow).
Good tank mates for bichirs:
- Large cichlids: Oscars, Jack Dempsey, green terrors (all roughly the same size)
- Large catfish: Plecos 6 inches or longer, synodontis catfish
- Larger characins: Silver dollars, larger barbs
- Other bichirs: Multiple bichirs coexist well when fed regularly and space is adequate
Avoid keeping bichirs with highly aggressive fin-nippers. The long dorsal finlets are a target for nippy species and are slow to heal once damaged.
Feeding
Bichirs are carnivores with poor eyesight. They locate food primarily by smell and movement. In the wild, they hunt invertebrates, small fish, and amphibians after dark. In captivity, this translates to a preference for meaty, sinking foods and a feeding window in the evening when they are most active.
- Base diet: High-protein sinking pellets or carnivore sticks, offered every other day
- Protein rotation: Frozen bloodworms, earthworms, shrimp, or fish fillet cut to size, 2–3 times per week
- Live food: Nightcrawlers are a favourite and good for enrichment; use only from pesticide-free sources
Feed only what the bichir consumes in 5 minutes, and remove uneaten food promptly. Bichirs will gorge if food is available, and overfeeding is the primary cause of ammonia spikes in their tanks. Twice-weekly targeted feedings rather than daily free-feeding produces healthier, longer-lived fish.
Breeding
Bichirs are egg scatterers. Breeding in captivity is uncommon but achievable in large, well-planted tanks. Males initiate spawning by cupping the female’s anal and genital region with their fin and fertilising eggs as she releases them among plant roots and substrate. The eggs are small, sticky, and scattered individually. Adults do not guard eggs and will eat them given the chance.
- Conditioning: Feed live or frozen meaty foods for 4–6 weeks; water temperatures on the warmer end of range (80–82°F)
- Setup: Dense plant cover (Java moss works well as a spawning medium); 10–20% water change with slightly cooler water to simulate rainy season
- After spawning: Remove adults promptly to a separate tank; eggs hatch in 3–4 days
- Fry first foods: Newly hatched brine shrimp, micro worms; fry are tiny but grow quickly
Common Problems
- Escape: The single most common cause of bichir death in home aquariums. Secure every gap in the lid, including filter and heater entry points.
- Fin rot: Caused by poor water quality or fin damage from aggressive tank mates. Keep nitrates below 20 ppm and treat with an antibiotic if the fin edge becomes ragged and dark.
- Bloat / overfeeding: Bichirs will overeat when food is offered too frequently. Their digestion is slow. Feed every other day, not daily.
- Missing the surface: If décor or a too-high water level prevents the bichir from surfacing, it will drown. Keep the water level 2–3 inches below the tank rim, and ensure the bichir can reach the surface from anywhere in the tank.
- Ich: Bichirs are susceptible to white spot. Raise temperature gradually to 82°F and treat with a half-dose of copper-based medication (bichirs are sensitive to copper at full dose).
Frequently Asked Questions
How big do bichirs get?
Size depends on species. The Senegal bichir, the most common species in fish stores, reaches 12–15 inches in captivity. Ornate bichirs and delhezi bichirs can reach 18–24 inches. Always research the specific species you are buying, not just the genus, because size varies dramatically across the 12+ Polypterus species available in the hobby.
Can bichirs live with other fish?
Yes, bichirs coexist well with fish that are too large to be eaten. The rule is: if the tank mate is longer than the bichir’s head, it is generally safe. Large cichlids, larger plecos, silver dollars, and other bichirs are all reasonable companions. Small fish and shrimp will be treated as food.
Do bichirs need a heater?
Yes. Bichirs need water temperatures between 75–82°F (24–28°C). Temperatures below 72°F suppress the immune system and cause respiratory problems. Unless your room stays consistently warm year-round, a reliable aquarium heater is essential. Use a separate digital thermometer to confirm the heater is holding the correct temperature.
How long do bichirs live?
Bichirs are long-lived fish. In well-maintained captive conditions with appropriate diet and water quality, they regularly reach 15–20 years. This is a significant commitment. A bichir purchased as a small juvenile may still be with you two decades later. Plan the tank size and care regime accordingly from the start.
Why does my bichir keep swimming to the top?
Surface trips are normal behaviour for all bichirs. They breathe atmospheric air using a primitive pair of lungs and must surface regularly to do so. A healthy bichir surfaces several times per hour. If you notice gasping combined with rapid gill movement, lethargy, or loss of appetite, test your water parameters, as those symptoms together can indicate ammonia or nitrite stress.
Equipment Recommendations
Bichirs need strong biological filtration to handle their heavy bioload. A quality canister filter is the best match for their tank requirements: high flow capacity, excellent mechanical and biological media space, and no surface agitation that disturbs the still-water setup bichirs prefer. Check our best canister filter guide for reviewed options at each tank size.
For heating, choose a heater with an external thermostat or a model with a reliable temperature hold. Bichirs are long-lived, and consistent temperature over years matters. Our best aquarium heater guide covers reliable options for tanks from 55 to 125 gallons. Use a separate digital aquarium thermometer to confirm the heater is holding correctly.
Don’t leave your bichir’s long-term health to guesswork. Schedule a monthly water parameter check with a reliable aquarium test kit, and catch any chemistry drift before it causes problems. Bichirs live 15–20 years; the right equipment makes that lifespan achievable.