Difference Between Pacu and Piranha


Main Difference

The main difference between Pacu and Piranha is that Pacu is mainly herbivorous freshwater fish, whereas Piranha is mostly omnivorous freshwater fish.

Pacu vs. Piranha

Pacu is a freshwater living creature that feeds on plants only, and that’s why pacu is called herbivore fish, while piranha lives on both plants and animals, so-called as omnivore fish. Pacu lives in the Amazon River, while piranha mainly lives in South America. The pacu relies on aquatic vegetation. In rare cases, pacu also eats snails and some insects. On the other hand, piranha feeds upon plants as well as snails and small insects.


Pacu is an incredibly peaceful creature as compared to the piranha; on the other hand, the aggressive behavior of piranha is mostly observed in starvation conditions. The teeth of pacu are small and blunt, so resemble human teeth; they are designed in a way to crush seeds and nuts. On the other hand, piranha’s teeth are sharp and razor-shape, strong enough to tear the flesh. The bite of pacu does not cause as much damage as piranha’s bite can cause.

When it comes to size, pacu is large as compared to the piranha. Pacu grows up to 28 inches, and its weight can reach 50 pounds, on the other hand, piranha grows up to 17 inches and can weigh about 7-8 pounds. One of the leading behavioral characteristics of piranha is hugely caring for their eggs; that’s why Around 90% of their eggs survive to hatch. Pacu permits their eggs to hatch on their own, conversely piranha stick tight to their eggs till hatching.


Comparison Chart

Deep-bodied, herbivorous, freshwater fish living in northern South America, is called pacu.Deep-bodied, omnivorous, freshwater fish living in South America, is called piranha.
Up to 28 inchesUp to 17 inches
Nearly 50 poundsNearly 7.5 pounds
Short, blunt and human-likeSmall, triangular and razor-shape
Mode of Nutrition
Herbivorous freshwater fishOmnivorous freshwater fish
Feed Upon
Aquatic vegetation, fruits, and seedsAquatic vegetation, fruits, seeds, snails, small insects
Lives as a single animalLives in gatherings
Caring of Eggs
Allows the egg to hatch on their ownStick close to their eggs
Less dangerousMore dangerous

What is Pacu?

Pacu is a freshwater fish that is herbivorous, which means that it lives on plants, including aquatic seedlings, seeds, and fruits. Pacu is less dangerous as compared to piranha and is exceptionally peaceful. Pacu’s teeth are more like humans. Its teeth are short, blunt, and less piercing as they only feed on aquatic plants. Therefore the bite of pacu is not that harmful or damaging.

Pacu is large as compared to the piranha. Its size reaches almost 28 inches, and its weight is nearly 50 pounds. Pacu is deep-bodied fish of northern South America and tends to live as a single animal, not forming colonies or gatherings. Therefore, pacu are also called as “lone wolf.”

When it comes to its eggs, pacu are less care for their protection. Pacu leaves the eggs to grow, develop, and hatch on their own. Therefore, the vulnerability of their eggs is higher than that of piranha’s eggs. Pacus (plural of pacu) mainly live on veggies, but in starving conditions, they may devour meaty meals, and that’s the case once in a blue moon. In feeding frenzies, both pacu and piranha become extremely dangerous.

Guppies and tetras are the best tank mates for pacu fishes, but as piranha related with quality feeds, so it does not feed on tank mates. After mating, pacu leaves their eggs to nourish on their own and finally hatch frying the fend for themselves. Pacu fishes are not endangered species and are edible.

What is Piranha?

Piranha is a freshwater fish living in the rivers of North America. It is an omnivorous creature that feeds on plants, i.e., aquatic vegetation, seeds, fruits, tubers, etc. but feeds on snails and small insects as well. Piranha has a reputation for feeding frenzies, which means that it becomes dangerous for the prey in starving conditions. The teeth of piranha are lesser, triangular, and blade-like, which means they are piercing enough to tear the flesh apart and inflict much damage.

One of the inherent features of piranha is in its extreme caring nature for its eggs. Piranhas stick close to their eggs until they hatch. Once they are hatched, they are deep-fried and concealed under plant covers until they have developed enough to swim independently.

Piranhas are schooling fishes, which means they tend to remain together in the form of groups or colonies while still young. However, some species of piranha separate themselves, becoming very regional. They mostly destroy the ecological balance due to their nature of forming colonies. When presented in a pond or stream, they breed in large numbers and feed on other fishes jeopardizing the possibility of other fish species.

Piranha raises up to 17 inches and weighs up closely 7.5 pounds. They have strong jaws with finely sawlike teeth, which makes them dexter at tearing flesh. Piranha are highly predative and mainly feeding on other fishes. Newly hatched piranha feed on phytoplankton and zooplankton and eventually move from smaller to larger fishes.

Key Differences

  1. Pacu is mainly herbivorous, while piranha is primarily omnivorous.
  2. Pacu lives in northern South America; on the other hand, piranha lives in South America.
  3. Pacu’s teeth are short, blunt, and human-like; on the contrary, piranha’s teeth are short, triangular, and razor-sharp.
  4. Pacu relies on aquatic vegetations, fruits, seeds, tubers, and plant seedlings, etc., on the other hand, piranha feeds on plants as well as animals, including insects and snails.
  5. Pacu is more dangerous as compared to the piranha; conversely, the piranha is more peaceful as compared to pacu.
  6. Bite of pacu is not as piercing as of piranha; on the other side, piranha’s bite inflicts more damage due to its strong jaws and sharp teeth.
  7. Pacu’s size is about 28 inches; on the contrary, piranha’s size is about 17 inches, which means pacu is larger than piranha fish.
  8. Pacu’s weight is about 50 pounds; on the other hand, piranha’s weight is just 7.5 pounds, which means pacu is more substantial fish than piranha.
  9. Pacu fishes are less care for their eggs; on the flip side, piranha fishes are more careful about their eggs.
  10. Pacus permit their ova to hatch on their own, whereas piranhas adhere closely to their eggs.


Pacu is an herbivorous freshwater fish, whereas piranha is omnivorous freshwater fish smaller in size as compared to pacu. The main difference between pacu and piranha is the mode of nutrition and behavior.

Aimie Carlson

Aimie Carlson is an English language enthusiast who loves writing and has a master degree in English literature. Follow her on Twitter at @AimieCarlson