Piranha Fish – Habitat, Care, Feeding, Tank Size, Breeding

Piranha fish belong to the Serrasalmidae family and are related to tetras, silver dollars, and pacu. They are multiple piranha species, and the common one in the aquarium is the red-bellied variety.

Larger species average at around 12 inches while smaller ones reach a mere 4 inches. However, most of them don’t grow bigger than 2 feet (60 cm) in length.

Good examples are the piraya piranha and red-bellied piranha which grow to an average of 20 inches (51 cm) long. The black spot species of piranha grow up to 11 inches (28 cm) in their natural habitat. Their lifespan also varies between 4 to 15 years.

Piranhas have a reputation for being aggressive and predatory, and their sharp teeth display an appetite for meat.

The fish are, however, unlikely to attack a person unless they feel trapped or threatened, or they are starving. If kept correctly, piranhas can be a very rewarding aquatic pet.

Piranha Fish Natural Habitat

Native populations of the piranha fish have been recorded in the Amazon River, rivers of Guiana, Sao Francisco River systems, Parana River, and the Orinoco Systems.

The fish likes white-water streams in lowland waters across South America, although they can survive in blackwater and clearwater. The Amazon river houses the most piranha species, and over 20 of them have been identified.

Piranha fish thrive in coastal rivers because of their feeding behavior. In addition to preying on smaller fish, piranhas also scavenge for carcasses left behind when ocean tides mix with coastal rivers.

The capture of piranha is illegal in some areas because of the risk of them being introduced in areas as invasive species. The fish has for, example, been recorded in the Kaptai Lake in Bangladesh.

Piranhas are naturally shoaling fish; they form schools of up to 30 fish to look for larger prey.

Piranha Fish Tank & Water Requirements

If you are looking to keep piranhas as pets, there are a few things to consider such as tank size, aquarium setup, filtration and water parameters. Below, you can find the water and tank requirements for piranhas:

– Tank Size and Placement

When it comes to piranhas, the bigger the tank, the better. It is recommended to keep one piranha in at least 30 gallons. A pair will, therefore, be comfortable in a 60-gallon tank.

Piranhas are a schooling fish, and you will need to keep them in a company of about four. The fish are also a bit timid and will feel most comfortable in a large setup.

Position your aquarium in a spot with low levels of light. Wild piranhas are adapted to dimmed areas since they live under the rainforest’s canopy. Try and place the tank in areas with little human traffic as the piranhas are shy.

– Substrate

You can either use a gravel-based substrate or smooth rocks for your piranha tank. Sand can also be used but it is hard to clean.

Piranhas are not substrate diggers, but you want a smooth one that cannot injure them. A darker substrate will provide an excellent contrast to the body colorations of the piranha fish.

– Accessories

Live plants complement a piranha tank well, but there is a chance that the fish will destroy them. You can use hardy plants as well as low-light varieties. Aquarists have had success with plants like Java fern, hornwort, and Java moss.

Piranhas appreciate plenty of decorations because they hide when stressed. You can use driftwood, where presoaking it will add a brownish stain to your tank that the fish seem to like. The darker color will, however, make it hard to spot your fish.

You can include PVC tubing and other aquarium-safe decorations. Piranhas love to swim around, and you should leave the center of the tank, the top, and the middle of the column open.

– Lighting

Piranhas are adapted to murky waters in the wild. Keeping them in bright lights will make them nervous and stressed, and you should try and dim the exposure. You can add floating plants to minimize the light, or just use natural light.

– Filtration

Piranhas are messy pets, and you will need a powerful filter, or several small ones depending on the size of your structure. You can choose between under-gravel, filter, or power filters.

– Water Conditions

The aquarium PH in a piranha tank should be between 6.5-7.8. The fish thrive in a temperature range of 75-80 °F. You may require a heater if the temperature in your house is below 75 °F.

Piranhas are sensitive to drastic water changes, and they will develop Ich if the temperatures are too low. Perform weekly water changes and use a capable filter to maintain the water quality.

Piranha Diet and Feeding Schedule


In the wild, piranhas live on an omnivorous diet, and you need to provide varied foods in the aquarium. Meat should be the base of their diet, and you can offer live or frozen tubifex worms, daphnia, blood worms, or shrimp.

You can provide feeder fish or even whole dead fish like lancetfish or silversides. Other meaty fish to consider include prawn, mussels, shed snakeskin, calamari meat, mice, and crab. Refrain from giving them pork, beef, or chicken because of potential diseases.

It is advisable to substitute the proteins with vegetables like leafy greens, spinach, zucchini, and potatoes. Avoid giving piranhas flakes or pellets.

You can feed adult piranhas once a day or once in two days.

Piranha Fish Tank Mates

Piranhas have a reputation for being aggressive, but some aquarists have reported success in keeping them in a community tank. The fish create hierarchical schools, where the most aggressive individual becomes dominant.

They will scout and claim the best spots in the setup and will be the first to feed. Any fish that attempts to challenge the dominance of the piranhas will be chased away or even be wounded.

If you must keep piranhas with other fish, buy larger species like black pacu, sailfin pleco, or striped raphael catfish. The Bristlenose plecos and common plecos are ideal tank mates since they have body armor to ward off attacks, and they live in the bottom tank areas.

Piranha Fish Breeding

It is almost impossible to discern a male and female piranha when buying them since the differences become apparent during spawning. Buy a couple of them to increase the chances of having both sexes.

Breed them in a dimmed tank with small pebbles as substrate. Piranhas can be seen making a nest by moving the substrate from the bottom. The male chases the female to the area that he has cleaned and fertilizes the eggs once they are laid.

Males are fiercely protective of their eggs, and juveniles are seen in about a week. Keep the young piranhas on a diet of live feed.

Female piranhas lay hundreds of thousands of eggs at one time. The eggs are laid in the sand just below the source of water where they live. This behavior is common among the red-bellied female piranhas which lay in nests dug by their mates.

Just like other fish, the male fertilizes the laid eggs. The fertilized eggs attach themselves to plants nearby. Usually, the attachment takes place at the bottom of a water source.

After just a few days, the fertilized eggs hatch into young piranhas. The parents fiercely protect the eggs and their young ones during the mating season.

Piranha Fish Behavior

Piranha’s existence is shrouded in mystery. This fish is portrayed differently from others for a simple reason. It is regarded as a vicious fish species with a tendency to hunt in large shoals.

This notion was derived from the belief that most piranhas created shoals for hunting purposes. But recent studies on this behavior has a completely different story from what was initially believed. It is suggested that these fish form schools to defend themselves against their natural predators.

Their well-known predators include other piranhas, water snakes, caimans, birds, turtles, otters, birds, and even human beings. In most cases, the young piranhas are the ones that bear the brunt of brutality from predators.

Piranha and Humans

There are many stories including movies that depict how dangerous piranha fish are to humans. On the contrary, these stories are not true. Reports of these fish biting humans in their natural habitats are rare. This means that their danger is highly blown out of proportion to create a bad picture of them.

But there are cases of people getting bitten by piranhas when they immerse their hands in aquariums full of them. This happens due to piranhas’ tendency to defend their territories by biting their opponents.

Contrary to stories about the voraciousness of these fish species, thousands of humans swim alongside piranhas in the same water bodies without being attacked or harmed.

Rumors about shoals of piranhas attacking horses or people and turning them into skeletons have become widespread all over the world. All these stories are inaccurate due to numerous exaggerations and re-tellings from one generation to another.

Even though piranha shoals can comprise up to a thousand fish in count, cases of biting humans are unheard of. There is no substantiated evidence of people getting killed due to a piranha attack.


Piranhas are certainly for the experienced aquarists, as they need customized care to thrive in an aquarium. Provide your piranha with a varied diet, plenty of hiding spots, dimmed lighting, and lots of swimming areas.

Monster Fish   Updated: May 1, 2020
avatar Hello, my name is Fabian, and I am the Chief Editor at Aquarium Nexus. I have over 20 years of experience in keeping and breeding fish. The aquarium hobby brings me immense joy, and I take great pleasure in sharing my experiences with others.

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