June 25, 2026, 2:13 pm | Read time: 5 minutes
Few animals have sparked such an internet craze in recent years as the capybara. These laid-back water-loving rodents have become cult figures as memes, plush toys, and social media stars. Yet, few know that the world’s largest rodents were once briefly declared “fish.” But that’s not the only curious fact about capybaras. PETBOOK presents 13 fascinating facts about these popular animals.
Capybaras Are the Largest Rodents in the World
With a length of up to 1.3 meters and a weight of around 70 kilograms, capybaras surpass all other rodents. Their robust bodies and slightly streamlined shape are perfectly adapted to their life between water and land. Despite their size, they appear remarkably gentle and calm–a perception consistently confirmed by their behavior.
Why Capybaras Are Considered “Fish” by Some
A curious anecdote: In the 18th century, the Catholic Church declared the capybara a “fish” in some South American regions after Venezuelan clergy requested it. The reason was likely their water-bound lifestyle–and the fact that this allowed locals to continue eating them during Lent. It’s a remarkable example of how culture and biology don’t always align.
Semiaquatic “Chill Masters”
Capybaras spend many hours each day in the water. There, they eat, rest, or escape the heat. Their eyes, ears, and noses are positioned high on their heads, allowing them to submerge almost completely while remaining alert. They feel so at home in the water that they are rightly considered semiaquatic “chill masters.”
Their Relaxed Temperament Is Legendary
Capybaras seem almost unflappable. Indeed, many studies show they have a very peaceful nature, and conflicts within the group rarely escalate. This is why they are often seen calmly lying with other animal species–whether turtles, ducks, or even caimans.
They Are Among the Most Social Animal Species in South America
In the wild, capybaras live in groups of usually 10 to 30 animals, sometimes even in herds of over 100 individuals. This is one of the reasons capybaras are not suitable as pets. They communicate through a diverse repertoire of sounds–whistles, grunts, barks, purrs–and maintain close contact with each other. This social network is essential for their well-being and protection.
Their Teeth Grow Throughout Their Lives
As true rodents, capybaras have constantly growing incisors. Since they consume large amounts of grass daily, these teeth naturally wear down, keeping them functional. However, if they are not sufficiently worn down, it can lead to painful problems.
Capybaras Use a Clever Digestion Trick
To extract all essential nutrients from their nutrient-poor grass diet, capybaras eat their own special cecum feces to digest it a second time. This process, known as caecotrophy, is not uncommon among rodents and other herbivores, but it is particularly effective in capybaras. This way, they maximize their nutrition.
Capybaras Enjoy “Wellness Treatments” from Birds
Capybaras are often seen with birds on their backs–and this is no coincidence, but a fascinating example of mutualism, or mutual benefit. Various bird species, including cattle egrets, starlings, and small sparrows, frequently land on capybaras to pick off parasites, ticks, and dead skin particles.
For the birds, this is a valuable food source, and for the capybaras, it’s a natural wellness service. They allow this procedure to happen with ease. Sometimes, entire groups of capybaras rest in the sun while several birds simultaneously sit on them and groom them–a peaceful interaction that rarely works as harmoniously in nature as it does with them.
Their Senses Are Remarkably Well-Developed
Capybaras have excellent hearing, which helps them detect even the faintest warning signals. Their eyes are ideally suited for detecting movement in the water, and their sense of smell aids in communication through scent marks. Despite their relaxed demeanor, they miss very little.
Capybara Young Grow Up in a True Community
The young are raised within the group, and all females take on tasks such as watching over or nursing. Youngsters are allowed to nurse from any mother, which increases their survival chances and strengthens the social structure. This cooperative behavior is one of the finest examples of capybara community spirit.
Their Apparent Smile Has a Real Background
Capybaras often appear to be smiling contentedly–and this expression is no accident. Their broad mouths and slightly curved snouts create the characteristic “grin” that makes them so endearing. This matches their nature, as capybaras in groups have demonstrably low stress levels. Their facial expression often reflects their inner well-being.
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Despite Their Popularity, They Are Not Safe Everywhere
While capybaras are not considered endangered overall, local populations suffer from habitat loss, hunting, and illegal trade, such as for controversial capybara cafés. However, in protected areas, their numbers recover well, highlighting the importance of intact wetlands for their survival.
Capybaras Love Hot Springs–Especially in Winter
The famous images from Japanese zoos show capybaras relaxing in onsens during winter. Although this behavior doesn’t originate from the South American wild, it aligns with their natural need for warmth and security. Warm water protects them from the cold, promotes their well-being, and reduces stress. No wonder they are seen there with closed eyes and their typical smile–it’s pure relaxation for them.