I have lived beside the rivers of the Peruvian Amazon for more than fifteen years, guiding travelers from Iquitos into places where maps lose their meaning and the forest decides the rules. Here, water is not just a feature of the landscape — it is the landscape. Rivers rise, forests flood, and entire worlds move with the seasons.
And among all the creatures that share this water with us, none commands more respect than the paiche.
The first time you hear one, you don’t see it.
You hear a deep, explosive breath — a sound like someone striking water with a paddle. The river surface breaks, and for a moment something ancient surfaces. Thick scales. A massive back. Red markings glowing in the low light.
This is the arapaima — the largest giant freshwater fish in the Amazon, and one of the most extraordinary fish on Earth.
Paiche, Arapaima, Pirarucu: One Fish, Many Names
Here in Peru, we call it paiche.
In Brazil, it is pirarucu.
In science, it is known as Arapaima gigas, the most famous of the arapaima species.
Different names, same presence.
The arapaima fish belongs to an ancient lineage, the Osteoglossidae family, a group so old that its anatomy feels closer to reptiles than modern fish. Fossil evidence suggests that arapaima ancestors existed millions of years ago, long before humans ever paddled these rivers.
When you guide long enough in the Amazon, you stop thinking of the paiche as a fish.
You think of it as a force.
The Giant Arapaima: Size That Commands the River
Scientifically speaking, the giant arapaima is among the largest freshwater fishes ever recorded.
But numbers alone don’t prepare you for reality.
- Length: commonly 2–2.5 meters (6.6–8.2 feet)
- Weight: 100–200 kilograms (220–440 lbs)
- Exceptional individuals: over 3 meters (10 feet) and nearly 220 kg
When a fully grown Arapaima gigas moves beneath a canoe, you feel it before you see it. The water displaces. The river shifts. Everything else gives way.
Ecologically, this makes the paiche an apex predator — a regulator of fish populations and a keystone species in floodplain lakes and slow-moving rivers.
Anatomy of a Living Fossil
From a scientific perspective, the arapaima fish is a masterpiece of evolutionary engineering.
Its most striking feature is its armor-like scales — thick, layered, and flexible. Studies have shown these scales can withstand piranha attacks, inspiring biomimetic research in material science.
Other defining adaptations include:
- An elongated, muscular body optimized for ambush predation
- A powerful tail capable of explosive acceleration
- A bony tongue lined with tooth-like structures for gripping prey
- A reduced reliance on gills
Which leads to the arapaima’s most famous trait.
Breathing Air: Why the Paiche Must Surface
The paiche is an obligate air-breather.
Its swim bladder functions like a lung, allowing it to extract oxygen directly from the air. In scientific terms, this adaptation evolved in response to the Amazon’s oxygen-poor waters — especially during the dry season when lakes stagnate.
Every 15 to 20 minutes, an arapaima gigas must surface to breathe.
That sound — the sudden, forceful gulp of air — is how fishermen track them at night. It is also how many paiche were overhunted in the past.
Evolution gave the arapaima an advantage. Humans learned to exploit it.
Feeding Ecology: What the Arapaima Eats
The giant arapaima is a highly efficient carnivore.
From field observation and dietary studies, its diet includes:
- Fish (primary prey)
- Crustaceans
- Aquatic insects
- Small reptiles
- Occasional birds or mammals at the water’s surface
The hunting strategy is a classic ambush: slow movement, precise positioning, and then a sudden suction-based strike that pulls prey into its cavernous mouth.
This feeding behavior supports rapid growth — one reason arapaima reach massive size in relatively few years.
Night on the River: The Arapaima After Dark
At night, the Amazon changes.
The forest breathes louder. Insects scream. And the paiche becomes more active.
The arapaima fish feeds aggressively after sunset, using vibration sensitivity and low-light vision to hunt. Its need to surface for air makes it audible even in complete darkness.
As a guide, I’ve learned to recognize individual fish by the rhythm of their breathing.
Slow breath.
Pause.
Another breath.
The river tells you who is there — if you listen.
Predators of the Paiche
An adult giant arapaima has few natural predators.
Occasionally:
- Large caimans
- Jaguars during extreme low water
- Large anacondas
But overwhelmingly, the greatest predator is humans.
Unregulated fishing nearly collapsed arapaima populations in many regions of the Amazon by the late 20th century.
Is the Arapaima Dangerous to Humans?
Scientifically and practically: yes, it can be — but not by intention.
The arapaima gigas is not aggressive toward humans, but:
- Its immense strength can cause serious injury if handled
- Defensive behavior increases during spawning season
- Sudden movements can overturn small boats
- Fisher injuries usually occur during capture or net removal
Respect, distance, and knowledge are essential when sharing water with this species.
Reproduction and Parental Care
One of the most remarkable aspects of arapaima species is their reproductive strategy.
During the dry season:
- Pairs excavate shallow nests
- Females lay up to 50,000 eggs
- Males guard the nest aggressively
- After hatching, males protect fry — often carrying them near their mouths
This level of parental investment is rare among large predatory fish and contributes significantly to juvenile survival.
Paiche and Indigenous Knowledge
Long before science described Arapaima gigas, Indigenous communities understood it.
The paiche has been:
- A vital protein source
- A symbol of strength and abundance
- A seasonal indicator tied to river cycles
Traditional management — fishing only at certain times, respecting breeding seasons — kept populations stable for generations.
Modern conservation is now rediscovering what the forest already knew.
Conservation Status and the Future of the Giant Arapaima
While the IUCN lists the arapaima as Data Deficient, local assessments in Peru and Brazil recognize severe regional declines.
Today, conservation efforts include:
- Strict fishing quotas
- Seasonal bans
- Community-managed lakes
- Sustainable aquaculture programs
When local people benefit directly from protecting the paiche, populations recover. I have seen it myself.
Lakes once silent now breathe again.
The Paiche as a Measure of the Amazon
The paiche is more than the world’s largest giant freshwater fish.
It is a living indicator of river health.
A survivor from deep time.
A reminder that the Amazon is not fragile — but it is vulnerable.
As someone who has spent years guiding on these waters, I know this:
If the arapaima fish continues to breathe in our rivers, the Amazon still has a future.
If it disappears — the silence will tell us we waited too long.
