The dinosaur bichir (Polypterus senegalus) is also called the Senegal bichir, gray bichir or dragon fish. It is a freshwater fish in the Polypteridae family, with a long, cylindrical body that reaches about 12 to 14 inches in an aquarium and is gray, beige or brown with darker blotches.
The name “dinosaur loach” (or “dinosaur eel”) is common in the pet trade, but this fish is neither a loach nor an eel. Bichirs are a separate, ancient group of ray-finned fish. This guide covers what the dinosaur bichir needs: a large, tightly covered tank, a meaty diet, and tank mates that are too big to swallow.
TABLE OF CONTENTS
Dinosaur Bichir Facts & Overview
| Scientific name | Polypterus senegalus |
| Common names | Senegal bichir, gray bichir, Cuvier’s bichir, dinosaur eel, dinosaur loach (trade name), dinosaur bichir, dragon fish, swamp dragon |
| Distribution | Tropical Africa, including the Nile system and West and Central African rivers (not India) |
| Size | Typically 12–14 inches (30–36 cm) in an aquarium; wild fish can grow larger |
| Life expectancy | 10–15 years (15–20 or more reported) |
| Color | Gray, olive, tan or beige with irregular dark blotches |
| Diet | Carnivore |
| Temperament | Predatory; eats anything that fits in its mouth |
| Minimum tank size | 55 gallons (about 4 feet long) |
| Temperature | 77–84°F (25–29°C) |
| pH | 6.2–7.8 |
| Hardness | Moderate; about 5–20 dGH |
| Care level | Intermediate |
| Breeding | Uncommon in aquariums; most fish are wild-caught or farm-raised from wild stock |
Is a Dinosaur Loach the Same as a Dinosaur Bichir?
Yes, in the aquarium trade “dinosaur loach” and “dinosaur eel” usually refer to the dinosaur bichir. Its body shape is eel-like, but it is not a loach or an eel. It belongs to the bichirs (family Polypteridae), which have lungs, thick scales, and a row of small dorsal finlets. If you are looking at a true loach, such as a clown loach or a kuhli loach, you are looking at a different fish.
Origin
The dinosaur bichir comes from tropical Africa, including the Nile system and many West and Central African rivers. It lives in lakes, river margins, swamps and floodplains, where the water is slow and often low in oxygen. The fish is not found in India.
Its lungs let it breathe air, which helps it survive in those conditions.
Adult Size & Lifespan
Most aquarium dinosaur bichirs reach about 12 to 14 inches (30 to 36 cm). Some individuals are reported larger, and wild fish can grow bigger. Females tend to be slightly larger than males.
Lifespan figures vary. References give about 10 to 15 years in captivity, and some keepers report 15 to 20 years or more with good care. Plan for at least a decade.
Availability
Most pet stores carry small dinosaur bichirs, usually for around $10 to $20 each depending on size and variety (albino forms cost more). Most fish in the trade are wild-caught or farm-raised from wild stock, so quarantine new fish. You can also buy them online from PetSmart, LiveAquaria, and Worldwide Fish and Pets.
Appearance & Behavior
The dinosaur bichir looks like a small prehistoric predator, but its slow, drifting movements make it easy to keep as long as you give it the right tank and mates.
Colors, Patterns, Fins, and Sex Differences
Dinosaur bichirs are usually gray, olive or tan with irregular dark blotches. Their bodies are long with thick, ganoid scales. The head is rounded, the nostrils are tube-like, and the pectoral fins sit behind and below the gill cover and are used to paddle along the bottom.
Instead of a single dorsal fin, bichirs have a row of 8 to 11 separate spiny finlets along the back, running into a rounded tail.
Juvenile bichirs have feathery external gills that shrink as the fish grows. Young fish can also be more strongly striped.
Males are usually slimmer and have a thicker, larger anal fin. Females are usually larger and rounder, but telling them apart takes a keen eye.
Typical Behavior
The dinosaur bichir is a predator that will eat any fish, shrimp or other animal it can fit into its mouth. This often includes fish much larger than the 3-inch limit people quote, so plan tank mates by mouth size, not by a fixed number.
It hunts by smell more than sight, so it sniffs around the bottom with its tube-like nostrils, and is most active at night or at dusk. It occasionally dashes to the surface to gulp air, since bichirs have a pair of primitive lungs and must reach the surface to breathe.
Dinosaur Bichir Care & Tank Requirements
Dinosaur bichirs are hardy and easy to feed, but they need a large tank, a tight lid and careful tank mates. This is why they work best for keepers who already have a bigger setup.
Habitat and Tank Requirements
Choose a long tank, not a tall one, because the fish lives on the bottom. Use sand, smooth rocks, driftwood and caves for cover. Plants such as java fern, anubias and java moss work well, and floating plants help dim the light.
A tight-fitting lid is essential. Bichirs are escape artists and can slip through very small gaps. Leave a small air space under the lid so the fish can breathe air.
What Size Tank Does a Dinosaur Bichir Need?
The old 29-gallon minimum is too small for an adult. Plan on at least 55 gallons, about 4 feet long, for one adult, and 75 gallons or more if you keep several or add tank mates. Younger fish can start in a smaller tank, but they grow quickly.
Tank Conditions
- Water type: Freshwater
- Tank size: 55 gallons or more, at least 4 feet long
- Temperature: 77 to 84°F (25 to 29°C)
- pH: about 6.2 to 7.8
- Hardness: moderate. About 5 to 20 dGH is reported.
- Substrate: soft sand
- Setup: smooth rocks, driftwood, caves and tough plants
- Filter: a strong filter. Bichirs produce a lot of waste.
- Surface access: required. They breathe air, so leave a gap between the water and the lid.
Disease
Dinosaur bichirs are hardy and are not prone to any one disease. The main risks are parasites on new wild-caught fish and problems from poor water. Wild-caught bichirs are known to carry gill and skin flukes such as Macrogyrodactylus polypteri, which can spread to tank mates. Quarantine new fish for several weeks and ask your seller about treatment.
Signs of trouble include scratching, a swollen belly, white patches, clamped fins and not eating. Smooth sand and clean water prevent most injuries.
Tank Mates
Bichirs are not aggressive toward fish that are too big to swallow, but they will eat anything they can fit in their mouth. Keep them with fish that are large, robust and not too active, and avoid small fish, shrimp and snails.
Choose tank mates that:
- are much larger than the bichir’s mouth, with deep bodies
- do not nip fins or bully slow fish
- do not compete for food at night
Tank mates commonly suggested for bichirs include:
- Other Polypterus of similar size
- Bloch’s catfish (Pimelodus blochii)
- Silver dollar fish (Metynnis argenteus)
- Lesser spiny eel (Macrognathus aculeatus)
- Black acara (Cichlasoma bimaculatum), with caution because cichlids can bully
- Bala shark (Balantiocheilos melanopterus), only when it is big enough not to be swallowed
Even compatible fish can fail if the tank is too small. If a tank mate is injured or missing, remove the bichir or the tank mate right away.
Diet and Feeding
Dinosaur bichirs are carnivores. In the wild they eat insects, crustaceans, small fish and other small animals. In the aquarium they accept earthworms, shrimp, mussels, bloodworms, pieces of white fish and sinking carnivore pellets.
Feed after the lights go out or at dusk, because they are nocturnal hunters. Sinking pellets and chunks of meaty food reach them on the bottom. Feed juveniles daily and adults a few times a week, giving only what they eat in a few minutes.
Avoid feeder goldfish and mammal meat. They can carry disease and are poor food.
Breeding
Dinosaur bichirs have bred in aquariums, but breeding is uncommon. In the wild they spawn during the rainy season. Females are reported to lay roughly 100 to 300 eggs over several days, which the male fertilizes and scatters among plants.
Keepers who succeed usually condition adults with a rich diet and large water changes, which is meant to mimic the rains. Move the eggs or the adults into a separate tank so the eggs are not eaten. Eggs hatch in about 3 to 4 days. The young have external gills and live off their yolk for the first week, then eat small live foods such as baby brine shrimp or worms. Sort the fry by size to limit cannibalism.
Should You Get a Dinosaur Bichir for Your Aquarium?
Get a dinosaur bichir if you have a tank of 55 gallons or more, can add a tight lid, and are comfortable feeding a meaty diet. It is hardy, interesting to watch and long-lived.
Skip it if you want a community tank of small fish, since those will be eaten.
Hi Robert, How are you, I have to catfish in my tank approximately 8cms. If I send you some pictures of them could you tell me the sex of them, I have tried but can’t figure it out. Thankyou, kind regards, Simone scholte.