Dinosaur Bichir Care: Tank Size, Food & Beginner Warnings

You may have seen a small dinosaur bichir beside tanks labeled “beginner fish.” That label can create an expensive, painful surprise. This fish grows large, hunts small tank mates, escapes through gaps, and needs a fully cycled aquarium.

Quick Answer: A dinosaur bichir needs a cycled 90-gallon tank, a sealed lid, and access to surface air. Keep water at 77–82°F, ammonia at 0 ppm, and nitrite at 0 ppm [1][2][3]. A 20-gallon tank only works as brief emergency housing for a tiny juvenile.

Updated July 13, 2026: This guide adds a fish-in cycling rescue plan for new keepers.

Is a Dinosaur Bichir a Good First Fish?

A dinosaur bichir is a poor first fish when cycling, equipment, and compatibility still feel confusing. It survives some mistakes better than delicate fish. However, survival does not equal good care.

The honest beginner answer

The fish needs a large tank from the start. It also needs meaty food, strong filtration, and a lid without gaps.

A beginner can succeed with careful planning. An impulse buyer with an uncycled 20-gallon tank faces high risk and fast costs.

• Choose this fish only if a 90-gallon tank fits your home and budget.
• Learn the nitrogen cycle before purchase.
• Plan for a fish that may live for decades.
• Keep small community fish in another aquarium.

Why stores make it look easy

Stores often sell juveniles near 3–5 inches long. Their small size hides the adult space requirement and heavy waste output.

The name “dinosaur eel” also causes confusion. This animal is a bichir, not an eel. Its care differs from typical beginner community fish.

Common Myth: “Bichirs breathe air, so dirty water cannot hurt them.” Reality: Surface air prevents suffocation. It cannot prevent ammonia burns or infection.

A safer decision rule

Wait if the tank cannot hold 90 gallons today. Waiting costs less than replacing fish, filters, and undersized tanks.

Choose a smaller beginner species if cycling still feels overwhelming. Return or rehome an impulse-bought bichir when proper housing cannot happen quickly.

Dinosaur Bichir Size and Basic Facts

Conflicting size claims confuse beginners because sellers display juveniles, while databases record much larger wild adults. Plan for a thick fish measuring 12–16 inches in many aquariums. Never assume a small store fish will stay small.

Name, appearance, and origin

Dinosaur bichir usually means Senegal bichir, or Polypterus senegalus. The NCBI taxonomy record confirms that scientific name [4].

It has an armored, gray-brown body and separate finlets along its back. Broad pectoral fins create its slow, walking-like movement.

Habitat clue: The species comes from African river basins, lagoons, swamps, and sheltered shore zones. Its shape suits slow searches along muddy bottoms [3].

Adult size and lifespan

FishBase species data records a wild maximum near 27.6 inches [3]. Aquarium fish often stay smaller, but sellers cannot promise a final size.

FishBase also reports captive lifespans of 34 years or more [3]. Even a shorter lifespan creates a major commitment.

Air breathing does not replace filtration

A bichir rises to gulp air with lung-like organs. That normal behavior lets it use low-oxygen habitats [3].

It still releases waste into the water. Therefore, the tank still needs a mature biological filter, regular testing, and partial water changes.

Dinosaur Bichir Tank Size and Setup

Equipment feels less overwhelming when every item solves one clear danger: waste, cold water, sharp décor, or escape. Start with the adult tank. Skipping temporary upgrades usually saves money.

Can a dinosaur bichir live in a 20-gallon tank?

No 20-gallon tank can house an adult dinosaur bichir responsibly. It lacks turning space, stable water volume, and enough room for waste control.

A tiny juvenile may need short emergency housing there. Upgrade as soon as possible, and test the water every day.

The beginner equipment checklist

Use a tank at least 4 feet long with an 18-inch front-to-back footprint. Larger footprints help long fish turn without bending tightly.

• Tight lid with every cable gap blocked
• Heater with a guard and separate thermometer
• Oversized canister or sump filter
• Fine sand or a bare bottom
• Smooth caves wider than the fish
• Liquid tests for ammonia, nitrite, nitrate, and pH
• Water conditioner and a gravel vacuum

A sealed aquarium lid protects an animal that pushes through small openings. Leave a humid air gap between the lid and water.

A Fluval FX4 canister filter offers substantial media space for many large tanks. Confirm its flow and capacity against the aquarium’s needs.

Arrange the tank safely

Place caves on the bottom before adding sand. This prevents digging from shifting heavy décor onto the fish.

Keep some open floor space. Use rounded wood and stones, since sharp edges can scrape the bichir’s belly and fins.

Pro Tip: If equipment choices feel impossible, buy the tank, lid, filter, heater, and test kit first. Decorations can wait.

Beginner CTA: New to large fish? Save this setup checklist before spending money at the pet store.

How to Cycle the Tank Before Adding a Bichir

Fish often die in new tanks because invisible ammonia rises before helpful filter bacteria become established. Clear water can still contain toxic waste. Testing matters more than appearance.

The nitrogen cycle in plain language

Fish waste and rotting food create ammonia. One bacterial group turns ammonia into nitrite, then another group makes nitrate.

Ammonia and nitrite harm fish. Partial water changes remove nitrate after the filter handles the first two compounds.

Cycle timing: The University of Florida ammonia guide says new biofilters often need six to eight weeks [2]. The guide also explains why test kits matter.

Fishless cycling steps

Fishless cycling protects the bichir from deliberate toxin exposure. The Merck Veterinary Manual supports adding an ammonia source before fish [5].

1. Fill the tank and add water conditioner.
2. Start the heater and filter.
3. Add pure aquarium ammonia to 1–2 ppm.
4. Test ammonia and nitrite every one to two days.
5. Redose only after ammonia falls near 0 ppm.
6. Wait until both reach 0 ppm within 24 hours after dosing.
7. Change enough water to lower nitrate below 20 ppm.
8. Add the fish, then keep testing during the first week.

Use an API Freshwater Master Test Kit instead of guessing from fish behavior. Liquid tests show problems before the fish collapses.

Emergency plan for an impulse purchase

Do not add ammonia when the fish already lives in the tank. Test ammonia and nitrite daily, feed lightly, and keep the filter running nonstop.

Change 25–50% of the water whenever either toxin appears. Match temperature and treat new tap water with conditioner.

The Royal Veterinary College nitrogen cycle guide warns that ammonia can kill aquatic pets [6]. It also warns against replacing all tank water during cleaning.

Pro Tip: Already bought the fish? Ask a healthy aquarium owner for mature filter media. Keep that media wet during transport.

What to Feed a Dinosaur Bichir

Beginners often lose fish by overfeeding, using feeder fish, or leaving meat to rot in an uncycled tank. A simple schedule protects both the bichir and the water.

Best staple foods

Use a quality sinking carnivore pellet as the main food. Add varied frozen or fresh aquatic foods for texture and interest.

Good options include:

• Sinking carnivore pellets
• Thawed shrimp pieces
• Chopped mussel or clam
• Earthworms from a safe source
• Frozen krill
• Occasional bloodworms for small juveniles

Wild Senegal bichirs eat insects, crustaceans, mollusks, frogs, and fish [3]. That natural diet supports animal-based aquarium foods.

How much and how often

Feed small juveniles once daily. Feed adults about three to four times weekly, based on body condition and leftovers.

Offer an amount eaten within roughly two to three minutes. Remove uneaten pieces quickly, since decay creates more ammonia.

Simple feeding rule: Feed near dusk, when the fish becomes active. Place food near its cave if faster tank mates steal meals.

Foods to avoid

Do not use feeder goldfish or minnows as a staple. They can introduce disease, and a single feeder species creates poor variety.

Avoid beef, chicken, and fatty mammal meat. Also avoid flakes as the main food, since most stay near the surface.

Common Myth: “A predator needs live feeder fish.” Reality: Prepared pellets and varied frozen foods provide safer, more balanced meals.

Dinosaur Bichir Tank Mates for Beginners

Compatibility advice conflicts because “peaceful” does not mean “too large to swallow.” A dinosaur bichir may ignore a tank mate for months. Growth can turn that fish into food later.

The safest beginner choice

Keep one dinosaur bichir alone while learning water care. This reduces waste, feeding competition, disease risk, and compatibility surprises.

A species-only setup also makes appetite changes easier to notice. Add tank mates only after the cycle stays stable.

Tank mate rules

Choose calm fish with deep bodies and adult sizes larger than the bichir’s mouth. Match their temperature needs and avoid crowded bottom space.

No species list guarantees safety. Individual size, hunger, tank space, and temperament can change every pairing.

Size matters more than friendliness

Never use current store size alone. Compare each animal’s expected adult size before purchase.

Avoid any fish the bichir can swallow headfirst. Also avoid sucker-mouth catfish, since some may rasp a bichir’s protective slime coat.

Add only one planned species at a time. Test ammonia and nitrite after every stocking change, because more fish create more waste [2].

Normal Behavior, Warning Signs, and Health

New keepers often mistake normal air gulps for dying, yet miss the real warning signs from poor water. Learn the difference before buying medication.

Normal dinosaur bichir behavior

A healthy bichir may rest under décor for hours. It often becomes active near dusk and explores by smell.

Regular trips to the surface for one quick gulp are normal [3]. The fish must always reach open air.

Slow walking motions with the pectoral fins are also normal. Brief fasting after a move can happen while the fish settles.

Test water before treating disease

Check temperature, ammonia, nitrite, nitrate, and pH whenever behavior changes. Water problems often look like infection.

The Merck guide describes new tank syndrome during the first six weeks [5]. Fish may become weak, stop eating, and die when ammonia or nitrite rises.

Watch for:

• Constant frantic surface trips
• Red or inflamed skin
• Cloudy eyes
• Open sores or fuzzy patches
• Rapid gill movement
• A swollen belly
• Loss of balance
• Refusal of several meals with other symptoms

First response

Perform a conditioned, temperature-matched partial water change when ammonia or nitrite appears. Increase surface movement without creating a harsh bottom current.

Do not mix random medicines. Contact an aquatic veterinarian when sores, swelling, balance problems, or rapid decline continue after water correction.

Common Dinosaur Bichir Mistakes

Most beginner disasters come from a few preventable choices, not mysterious bad luck. Fix housing and water before blaming the fish or buying medicine.

Mistakes that cause fast trouble

The worst mistake starts with a small, uncycled aquarium. A growing predator adds waste faster than a new filter can process it.

• Keeping the adult in 20 or 55 gallons
• Leaving gaps around filter hoses
• Adding fish before the cycle finishes
• Replacing all filter media at once
• Rinsing biological media under untreated tap water
• Feeding until the belly becomes greatly swollen
• Choosing tank mates by friendliness alone
• Using sharp gravel or unstable rock piles

Cleaning without destroying the cycle

Beneficial bacteria live mainly on filter media and other wet surfaces. Preserve that media during routine cleaning.

Rinse sponges gently in removed tank water. Replace only worn media, and never replace every biological section together.

Simple cleaning target: Change 25–40% weekly as a starting schedule. Adjust that amount using nitrate readings, feeding, and stocking.

Buying before planning

A sale price covers only the fish. The adult tank, stand, filter, heater, lid, tests, food, and water care cost far more.

Never release an unwanted bichir outdoors. Contact the store, a local aquarium club, or a responsible large-fish keeper.

Beginner CTA: Ready to start safely? Complete the cycle checks before bringing a dinosaur bichir home.

Conclusion

If fish keep dying, pause new purchases and make water testing the next action. A dinosaur bichir can thrive only after the aquarium handles its waste safely.

The safest path forward

Use a cycled 90-gallon or larger tank with a tight lid. Maintain 77–82°F, 0 ppm ammonia, and 0 ppm nitrite.

Provide smooth caves, open floor space, strong biological filtration, and clear surface access. Feed sinking carnivore foods in controlled portions.

Beginner stocking rule: Keep the bichir alone at first. This choice simplifies care and protects small community fish from predation.

If the fish came home today

Begin daily water tests and partial changes whenever ammonia or nitrite appears. Feed lightly and keep the filter running continuously.

Arrange a larger tank or responsible rehome immediately if current housing cannot meet adult needs. Acting early protects the fish and saves money.

Bottom line: The dinosaur bichir rewards patient preparation, not impulse upgrades. Build the safe system first, then bring home the predator.

Sources

Conflicting store and video advice becomes easier to judge when each claim traces back to fish or veterinary references. These sources support the identity, biology, water targets, and cycling guidance above.

How the references were used

FishBase supplied habitat, temperature, diet, maximum size, air-breathing, and longevity data. NCBI confirmed the accepted scientific identity.

University of Florida specialists supplied ammonia and biofilter guidance. Merck and the Royal Veterinary College supplied clinical guidance about new tank syndrome and cycling.

How the care target was chosen

The 90-gallon recommendation adds a conservative captive-care margin. It accounts for body length, turning space, waste, and beginner maintenance needs.

No single tank volume removes the need for testing. Larger adults, crowded stocking, or limited floor space may require 125 gallons or more.

Source publication dates differ, so the article separates measured biology from practical aquarium recommendations. Water tests and the fish’s adult dimensions should guide final choices.

Reference list

1. Aquariadise: Dinosaur Bichir Care
2. University of Florida IFAS: Ammonia in Aquatic Systems
3. FishBase: Polypterus senegalus
4. NCBI Taxonomy: Polypterus senegalus
5. Merck Veterinary Manual: Management of Aquarium Fish
6. Royal Veterinary College: The Aquarium Nitrogen Cycle