A close up of piranha fish scales

Do Piranhas Have Scales?

Talking about Piranha, most people think of a ferocious mindless killer. The media and movies have exaggerated behaviour for effect, but what about their anatomy, principly their exterior.

So, do Piranhas have scales? In short, yes possess scales. Al species of Piranha are scaled fish. They provide armor protection, keep fungi and bacteria at bay as well as evenly distributing the body mucous to aid in more efficient swimming.  Piranha are always losing their scales in brushes with underwater foliage and attacks, but the scales regenerate. Each species produces a unique scale, which makes each species of Piranha identifiable by their scales. 

Piranha Overview

Piranha are a genus of toothed fish with around 60 species that is actually omnivorous, not carnivorous as is commonly thought. Typically thought of as an indiscriminate bloodthirsty and ferocious killer it as actually a rather shy and timid fish.

Piranha are indeginous to Latin America, with the most commonly referred to as the Red-Bellied Piranha. They have an average size of around 12 to 14 inches and weigh around 8 lbs in weight.

There are 4 species of Piranha, Pristobrycon, Pygocentrus, Pygopristis, and Serrasalmus who share common characteristics.

A close up of the red bellied Piranha

Piranha Anatomy

Piranha are most common in the Amazon basin lowlands, and are not to be found in the mountainous areas of Chile or Peru, typically above 3,500 m.

They are a freshwater tropical fish, surviving in the clean white watres of the various rivers, including the Amazon river, the Orinoco river, the Guyana river, the Sao Francisco river, the Rio Negro and the Paraguay river.

They are non migratory and do not to the ocean, where they would not survive.

Piranhas have round scales that entirely cover their body. These scales are being lost continually. They frequently lose them in tussles and fights with other fish. They environment can be rough with rapid water and the constant moving in and out of foliage to evade predators.

These scales are regenerative to replace the lost scales which produce a slimy mucus. This mucus makes them feel rather slippery but aids waterflow over the body and overall helps promote the health of the fish.

The black Piranha is the biggest Piranha and can grow to around 20 inches, perhaps even slightly bigger. They can weigh up to 10 lbs at tat size and have a top speed of around 25 mph in bursts.

What most people know about Piranha is that they are a toothed fish. Even the name ‘Piranha’ is taken from the Brazilian language of the Tupi and literally means “toothed fish”.

A close up of the red bellied Piranha

What Actually Is A Fish Scale

So, what exactly is a fish scale?

The scale of a fish is described as a small rigid plate that grows out of the skin of a wide variety of fish. Most fish produce scales as they evolutionarily useful. They can provide color, which can act as camouflage as well as a barrier for protection.

Piranhas produce scales that are individually identifiable to a specific genus of the fish. That is, you can identify a Red-Bellied Piranha by its scales.

In humans, the same type of genes that develop hair in all mammals are involved the scale development in fish.

A close up of piranha fish scales

What Do Piranha Scales Do

While some fish possess scales and some don’t, the Piranha is blessed with scales. So what function do they provide and how useful are they to the Piranha?

Armor protection: First and foremost, scales on any fish, not just the Piranha provide a level of protection to the body. Mainly against predators, although there are scale eating Piranha. Additionally the Piranha will brush up against underwater roots and rocks so plates help keep the body protected.

Health protection: Scales help keep an even layer of mucous that is produced over the whole body of the fish. This ‘slimy barrier’ keeps bacteria, fungal infection or a parasite infection. 

Swimming efficiency: The scales being small thin plates in line with the body, along with a secreted mucous layer help reduce the drag of water flow over the body. This means the fish can expend less energy holding still against a current and increases the available top speed.

Some Piranha Feed On Scales

Most piranha are omnivorous. There are some vegetarian Piranha, but most feed on a diet of worms, fish, insects, crustaceans, fruits, nuts and seeds.

They will take meat from large mammals such as cows only if it is carrion, and already dead. Or they are extremely hungry, such as takes place in the end of the dry season.

The Red-Bellied Piranha has been calculated to eat around 2.46 grams of food per day.

During times of extreme hunger, the Red-Bellied Piranha, as well as the other species are known to fin nip or scale nip for food. That is, take small bites out of other fish to survive. This can happen in times of stress as well.

However, the wimple Piranha (Catoprion mento), which is not a ‘true Piranha’ actually feed on fish scales. The scales are particularly nutritious it seems.


So, yes, All species of Piranha have scales. They are round rigid plates that are lost by the fish for a variety of reasons. They are regenerative, and the Piranha replace scales as they lose them throughout their entire lives.

They provide armor protection, aid the health of the fish, and make swimming more efficient.

During times of hunger, Piranha will ‘scale nip’ and ‘fin nip’ to keep starvation at bay. Scales are unique to each species of Piranha, which can be identified to a species.

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