Piranha Fish: A Guide to Care, Breeding, Diet & Behavior

Piranhas are strange-looking, aggressive fish but fascinating to those who breed and raise them. These interesting piranha fish fascinate fishkeepers with their tough jaw strength, approximately 40 teeth, and long life span.

Many parts of the world have banned breeding, selling, and owning most species of piranha fish, so it’s important to check your country and state laws before purchasing them. In addition, raising piranhas is not as easy as your think. They require an omnivorous diet and a lot of room to move and grow.

If you fancy Piranha and want to get your toes wet in terms of breeding and raising Piranha, then this guide is for you!

Piranha Fish Overview

Pirahna fish are mostly found in the Amazon basin. Their name originates from the indigenous Brazilian Tupi language, meaning ‘toothfish.’ There are 30 sub-species of Piranha fish in various colors such as blue, green, red, silver, black, or brown.

These aggressive freshwater fish won’t attack your fingers and toes, and many Brazilians and Perusian swim without fear of piranhas. However, they can become aggressive when hungry and attack in schools, such as large, dead animal flesh. Their diets primarily include fruit, plants, fish, and insects.

Pirahna is famous for its sharp triangular teeth visible on the upper and lower jaw. While Hollywood has given them a bad reputation with movies such as the various Piranha movies, you will find that they will only attack if they feel threatened. They are schooling fish and can overwhelm their prey, making it appear more intimidating. The muscles that form the jaw are around 2% of its body mass, which gives Piranha such a potent bite.

Where does Piranha get their teeth from?

Studies show that Piranha relatives had two rows of teeth used for breaking nuts and seeds, but the Piranhas only have one row of interlocking teeth. One of the Piranha’s relatives with the same teeth is the extinct ‘Megapiranha’ which lived millions of years ago.

The Megapiranha was much bigger than today’s Piranhas, and their bite was significantly stronger. They were also thought to be flesh-eating fish, and their teeth were arranged in a zigzag pattern.

Piranhas can live around ten years, but some have recorded their fish living up to 20 years.


You can characterize piranhas by their infamous two rows of triangular, sharp teeth that are firmly packed on both jaws. In addition, they have a saw-edged belly and blunt heads, making them easily recognizable. The teeth are around 4mm long and sharp enough to bite through bone.

There are multiple species, and they come in many colors, such as all-black, yellow, grey, and silver, with orange bellies. Their average weight is around 10 lbs, and they can reach a length of 12 inches. However, some species might be heavier and longer.

There are many different species of piranha fish, but these are the most commonly raised in fish tanks:

  • Red-bellied Piranha: These are the most commonly raised piranha species by fishkeepers. They can grow to around 13 inches long and have a beautiful, shimmery silver color with red and orange on the lower parts of their body. They thrive in groups, so you will need enough room for a fish family.
  • Black spot Piranha: As the name suggests, this species has a black spot on the back of its head. They grow to around 11 inches or less and will do well with a small group of 5 or 6.
  • Red-eye Piranha: While these Piranhas grow to around 17 inches, they like to live alone and thrive in a good 75-gallon tank. They are usually a solid silver or black color with red eyes.
  • Pike Piranha: The Pike Piranha has a longer shape than other species and a shimmery silver color. They are aggressive in nature and should be kept alone because they don’t tolerate other fish, including their kind.
  • Gery’s Piranha: This rare Piranha grows to about 12 inches and has a slim, silver body. They have a clear broad strip from their mouth to their dorsal fin. Grey’s Piranha can live alone or in a school successfully.


In their natural habitat, Piranha thrives in coastal streams across South America because of their feeding behavior. They prey on small fish and carcasses that the tides bring in from the ocean. While they are aggressive fish, Hollywood has portrayed Piranhas as vicious creatures that will attack humans on a whim, which is far from reality.

Researchers have determined this behavior is for protection against predators. It is rare for Piranha to bite humans in their natural habitat. On the contrary, fishkeepers have reported Piranha bites when their hands are placed in an aquarium full of Piranha, mainly because they defend their territory.

The various species of Piranha have different behavioral characteristics. For example, some species like the Red-Bellied Piranha live in large groups while others prefer to live alone and may show aggressive behavior when added with their own kind or other fish.

Diet and Feeding

Since Piranhas are omnivorous, they require varied foods to maintain a healthy diet once a day. While meat is the main portion of their diet, you can also feed them:

  • Daphnia
  • Blood worms
  • Shrimp
  • Tubifex worms

You can feed your Piranhas dead fish, such as prawns, mussels, and crab. Avoid chicken, beef, and pork as they may carry diseases that can kill the Piranha. Along with meats, give Piranha vegetables, such as spinach, zucchini, and other leafy greens.

Piranha Fish Care Instructions

Piranha Fish Care

Piranha flourishes in large tanks and will school to protect themselves from predators. In addition, they like to hide, so adding many plants will make their day-to-day living more enjoyable. Avoid crowding the tank too much, and add about four fish in a large tank. If they get too cramped, you might find your fish being jumpy and attacking one another.

Piranhas love to eat, which means they produce a lot of waste, so you will need a good filtration system, and the water must get changed every week – at least 30% should be removed and replaced. Also, consider adding a screen to the top of the tank so fish cannot jump out when they’re hungry or display aggressive behavior.

Tank Setup

When finding the perfect place to set up the tank, consider keeping it out of the sun, as it can foster germ and bacteria growth. Also, since Piranha is aggressive and territorial, they need a peaceful environment that won’t stress them out. They are used to dirty water surrounded by a canopy of rainforest trees, so they aren’t used to lit areas.

Tank instructions:

  • Water temperature: There must be a 75-80 degrees Fahrenheit constant water temperature. Piranhas don’t tolerate major water changes, so keeping their temperature consistent is essential. Ensure there is a thermometer in the water to keep track of any temperature changes.
  • pH: Tank water pH should be 5.5 – 8.0.
  • Filtration system: A strong filtration system is required to discard the waste.
  • Decorations: Add smooth gravel, driftwood, plastic, and live plants to help them feel protected. You can add rocks, such as granite and basalt.

Plants that can get added include hornwort, Java fern, and moss, but know that Piranha will most likely destroy the plants. Driftwood will give the water a nice stain to the water which Piranha prefers. Fishkeepers have also included PVC pipes as decoration and hiding spots for Piranha in their aquarium.

Breeding Piranhas

When buying young Piranha, it’s challenging to determine which are male and which female. So buy several fish to increase your chances of getting both sexes. The tank needs to have little light and small pebbles as a substrate which Piranhas will use to make nests. The male Piranha will chase the female to where he wants her to lay the eggs, and once she gets done, the male will fertilize the eggs.

Females can lay thousands of eggs in the nests the males create. Males are highly protective of the eggs, and you will be able to see the juveniles within a week. Sometimes the fertilized eggs will attach to plants. Once the eggs hatch, feed juveniles live feed so they can thrive.

Don’t have other fish species in the same tank with breeding Piranha because they will be seen as a threat to the group, killed, and consumed.

Final Thoughts

Keeping Piranha fish can be difficult for novice fishkeepers. They need to be well-fed to avoid aggressive behavior, and you might have to have a permit to keep them. Be sure to check state laws on raising and breeding Piranha.

Piranhas love natural, spacious environments and don’t do well in confined aquariums. Give them plants and wood to emulate their natural environment to ensure they grow, breed, and live well. In addition, Piranha isn’t migratory animals in the wild, so when conditions are right, they will thrive. Keep the temperature consistent and clear the waste regularly.

Piranha can survive 10 – 20 years, so this is a long commitment and requires dedication to their care and constant monitoring.