4 red bellied piranha in an aquarium tank

Pet Piranha Care: Do Piranhas Make Great Family Pets?

There’s both a curiosity and a fascination that comes with owning a pet Piranha. They are actually quite shy fish, and don’t behave in the way the have been portrayed in films. Owning and keeping pet Piranha is not like owning your own James Bond villain lair.

Fishkeepers all over the world keep pet Piranha with relative ease, most without losing any digits, so you should know that despite their reputation, they are not particularly difficult fish to keep.

Although there are said to be around 30 to 60 species of Piranha, only a few are kept as pets. The most common, by far, is the Red-Bellied Piranha, considered the most aggressive and dangerous of the species. Presumably, that’s the attraction.

So, if you are wondering how to care for Piranha, how difficult they are and what you need to do to keep them healthy, then read on.

Quick Overview: Piranha At A Glance

  • Family: Characidae
  • Temperament: Dangerously aggressive
  • Max Size: 12 to 24 inches, depending upon tank size
  • Water conditions: Freshwater, Tropical (71.5 ° F to 82.5 ° F ), pH 5.5– 8.0
  • Care level: Diligent
  • Diet: Omnivore
  • Minimum tank size (as adult): 30 gallons for one, 60 gallons for schooling fish

Piranha Introduction

Ask almost anyone and they think Piranhas are both blood crazed, vicious, and are aggressive killers. Despite this, they are a reasonably popular form of pet fish, or maybe it’s even because of it.

There is a growing awareness and interest in keeping them as pets. With a lot of misinformation out there, it’s as important as ever to be aware on how to keep Piranhas safe and healthy in a home aquarium. Piranhas are a pretty tough fish, after all they survive in the harsh environments of the Amazon basin. They are neither difficult , nor dangerous fish to own is kept correctly.

If you browse the internet, have a look at aquariums, visit online fish stores or even visit a local pet store that deals with Piranha it quickly becomes evident that the most common breed owned is the Red-Bellied Piranha. Although there are many plant eating Piranha, most people want to own the carnivores so both the Red-Bellied, Redeye and Silver Piranha are most common. The attractive feature appears to be that they are carnivorous.

piranha fry in an aquarium

Something that may come as a shock to new Piranha owners is just how big these things can grow. When you buy Piranha for a tank, typically they will be in the ‘fry’ stage and just be a few inches in length. They’d normally be the same sort of size as other types of fish at the point of purchase. Sometimes this isn’t mentioned when you but Piranha fry but something to take into consideration when you plan them as pets.

The problems that can ensue from this should be rather obvious. A Piranha in a tank can easily grow into a 10 inch fish. If you have a few and the tank is too small this provides cramped and eventually stressed fish. Only this stressed fish has teeth and is an omnivore. The larger Piranha can grow to 24 inches in length quite easily. Thus a large tank is mandatory for owning these fish, even if you buy them from fry.

Thus when selecting an aquarium to house your Piranha it should be the largest you can afford. It’s generally recommended that around 60 gallon tanks be the minimum for a few fish, with an additional 20 gallons per extra fish. Although, this is a very rough rule of thumb as it depends on the species.

The species within the Pygocentrus species, a genus of the Piranha family that includes the famous Red-Bellied Piranha are a schooling fish, meaning they will swim around together. Well experienced Piranha keepers suggest that owning a single Red-Bellied Piranha produces a fish that hides all day and only emerges from the shadows in order to feed. Thus you have a Piranha exhibiting very little Piranha behaviour, the very reason you might have purchased them in the first place.

It’s also suggested, or at least a topic for debate, that only two fish will also result in a similar scenario. The reason is that there is a good probability that the two fish will turn on each other at some point during their development, as they establish dominance and one will kill off the other.

Experienced Piranha keepers, for Red-Bellied Piranha suggest 3 or more Piranha for best results which means at least a 60 to 80 gallon tank. The bigger the better.

Despite the above there are no iron-clad rules for Piranha ownership. Occasionally, a single Piranha is fine and there are people who keep more than 8 Piranha in a 100 gallon tank.

The recommendations are based on ‘best practices’ not a guaranteed result or instructions. The only thing is that if you cramp the fish into a tank that is below best practices, you increase the risk of stressed and thus unhealthy fish. Try to imagine living in a studio flat with 5 other people. Possible, just not really ideal. It’s the same with Piranha keeping. The best practices are designed to help you replicate natural Piranha behaviour.

Producing stressed and unhealthy fish is likely to increase the risk of fatalities to reduce the stress. It is strongly recommended to have as large a tank as you can to reduce Piranha stress levels. They can sort territorial disputes and dominance fights by moving away from one another. The less stress they have, the more likely they are to behave naturally, which means they will swim around the tank.

There are exceptions to this though (who said Piranha keeping is easy?). The Serrasalmus genus of Piranha (includes the Black Piranha) are recommended to be kept on their own. In there natural habitat they travel alone.

The black Piranha of the Serrasalmus family should be kept in a large tank and kept alone, with no other fish in the tank. These are aggressive fish that are alone naturally in the wild, and will treat other fish in the tank as an intruder. It matters little whether they are fellow Piranha or not.

These fish will attack a lot of things to protect their territory. Occasionally even aquarium equipment. With more than one in the tank you would need to provide a larger tank then normal and plenty of hiding places so they could keep away from each other. Additionally a very regular feeding discipline would be necessary to keep the fatalities at bay.

A good guide is that if a reputable Piranha seller sells fry in a shoal or individually might be a good indication as to whether they should be kept with other fish.

An Overview of Piranha Care

With the idea of keeping Piranha being both unusual and interesting, it is gaining in popularity with the public. Especially, as some of the more egregious myths out there are more easily debunked. In real life it will be both rewarding and fascinating provided you remain committed to the healthcare of your fish.

Firstly though, due to governmental concerns about them being turned loose in an ecosystem which they might thrive, you will have to check whether owning Piranha in your location is permitted. For the US, please check out this article, to find out the requirements of owning Piranha.

Assuming you have legal authority to keep pet Piranha, your next concern out to be how to keep healthy and stress free fish. They are certainly unusual enough to stop the conversation when you mention your hobby to people. By far the most common type owned in home aquariums is the Red-Bellied Piranha. Although being omnivores, not carnivores by nature, they should be fed plant matter as well as meat and worms.

Whilst you can get Piranha from online aquatic stores, or from local pet stores, another option is to consider finding a fellow Piranha keeper and seeing if they have any for sale. People sometimes buy too many, or need to get rid of them for a variety of reasons so it can be a source of good quality fish.

A large tank, the largest you can afford is a must. Serious keepers don’t use small tanks, even if it is for just one fish. These fish are native to Latin America and thrive in clean freshwater. A horizontal tank, not a fancy shaped aquarium, with good simulated current flow helps them enormously.

Left alone, in a healthy environment, with regular feeding, Piranha will swim about the tank, moving cautiously against the slight current. They will shoal if they are from the right genus and you will have a well balanced tank. If you introduce another fish to the tank, the situation can be quite different. Sensing they might be under attack they might attack first. It can be quite a show.

Whilst they swim generally around your tank, you can quickly become lulled into a sense this is just another fish. When they attack, if they feel they are under threat, you quickly get a different appreciation for the fish. Foreign bodies to the tank are quite often not tolerated.

Thus fingers should not be presented in the tank, even in jest or as an act of bravado. These fish, with a burst of power can easily reach 15 to 25 mph and in a tank that is around 50 inches long, it is not long before they can take a bite out of your fingers. So, never, ever allow people to fool around with Piranha. Control of the tank is exceptionally important.

Piranha are not a pet to have if children who might dip their fingers in a tank unknowingly, or an unwise guest likewise. The location of your tank should be in  a place where you can control access to minimise the chances of an injury occurring.

Piranha Appearance

What Size Are Piranhas When They’re Small?

When they are very young, they hatch from eggs and will be very small. As they grow towards being juvenile piranha, they will be around 1 to 2 inches in length. Most Piranha bought are segregated into the categories of under 1 inch, 1 to 2 inches and 2 to 4 inches. Ten Red-Bellied Piranha under 1 inch are around $80. Ten Red-Bellied Piranha under 2 inches will be around $120.

Exactly How Fast/Slow Should You Anticipate Piranhas to Grow?

Piranha seem to have a growth spurt early on and then slow down. An adolescent Piranha will grow at around an inch per month until around 7 or 8 inches in length. As they become young adults they then grow at 1 to 2 inches per year. They will grow in accordance with the capacity of the tank, and they will grow in width as well.

What’s A Piranha’s Maximum Size in Captivity?

In the wild, a Piranha cam reach around 24 inches in length and weigh around 5 kg. This is quite a hefty fish. Luckily, in captivity, they will not grow to quite such a size. In a standard home aquarium it’s not unusual for them to get around 10 or 12 inches in length. It should be around 3 to 5 years before they reach this size.

Common Varieties of Home Piranha

There are 2 main Piranha that are kept in a home aquarium.


  • Red-Bellied Piranha
  • Black Piranha, also known as Redeye Piranha


The Red-Bellied Piranha is aptly named. When they are young they are mainly silver-gray that develop a little red patch on the ‘belly’, along with red pectoral and pelvic fins. With male Piranha their red bellies are a little less bright. The females tend towards having the brighter colors.

adult red bellied piranha in corner of a tank

Are Piranha Dangerous?

When people consider owning Piranha, mainly due to a lot of misconceptions from the movies and the media, they will often ask about the risk of injury when owning them.

Whilst not as benign as bunny rabbits, and they can bite you if you are almost recklessly uncareful, the idea that they are just waiting to pounce on unsuspecting fingers is a great myth. They are rather shy creatures that move away from larger animals. The great stories of Piranha devouring people in minutes are the stories of current myths. They simply don’t behave that way.

As you will no doubt witness, even in the wild they are considered timid fish and are in a constant state of nervous fear, with Piranha being the meal for many an Amazon creature, from birds to caimans.

Red-Bellied Piranha in a tank will therefore school for safety. Contrary to the more exciting myth, Piranha are better protected in numbers, rather then being solo fish.  They do not school for ‘pack hunting’ reasons.

The myths started really with Theodore Rossevelt, where it seems he was treated to a ‘staged event’ that made Piranha look crazy. The locals in order to impress are supposed to have starved Piranha in a section of the river before pushing an unsuspecting cow to the water’s edge. The water is supposed to have erupted with fury at the sight of several thousand Piranha in a feeding frenzy.

In reality this sort of behaviour is rare. Piranha steer clear of large mammals and any attacks have been when their nests have been threatened or during the dry season when there is food scarcity.

In a home aquarium, this means that you are not really in any serious danger. Whilst there are more aggressive species, and you can certainly under feed them, no bite will call a fatality. You are quite safe if you have a healthy respect for them and don’t provoke them.

Is it Legal to Maintain and Own a Pet Piranha?

There is no static answer to this question, as rules are subject to change at any time. It greatly depends upon where you live. As well as some states in the USA, Piranha are illegal in the Philippines, Malaysia, Germany, Mexico, and Australia.

Currently, in the US the States that prohibit the sale of Piranha are;


  • Alabama
  • Alaska
  • Arizona
  • Arkansas
  • California
  • Colorado
  • Florida
  • Georgia
  • Hawaii
  • Kentucky
  • Louisiana
  • Maine
  • Massachusetts
  • Mississippi
  • Nevada
  • New Mexico
  • New York
  • North Carolina
  • Oklahoma
  • South Carolina
  • Texas
  • Utah
  • Virginia
  • Washington

Piranha: To Like or Not to Like?

Although closely related to the pacu, they are in fact their own species, they belong to the family Serrasalmidae. There are said to be between 30 to 60 known species, depending upon how you classify them,

By far the most common Piranha found in home aquariums is the Red-Bellied Piranha (Pygocentrus nattereri). They are easily recognised, but other common species in a home aquarium are black Piranha, and wimple Piranha.

Almost all species are not quite as dangerous as the media, government legislators and films would lead you to conclude. They are omnivores so can survive quite happily on a lot of types of food. Fruits, seeds, plants and flakes can all be used to feed your Piranha.

If they are kept healthy and happy, with proper conditions they are a spectacular fish that are an amazing sight to behold. Proper care takes a devoted owner, but they are not a difficult fish to own provided your tank is set up correctly and you commit some time towards their well being.

What’s The Very Best Species of Piranha to Keep as a Pet?

The Red-Bellied is the commonly kept, probably because it is considered the most aggressive. If you are going to own Piranha, why not own the interesting one it seems. But is this correct?

With up to 60 species to choose from, most people don’t really want to own the herbivores amongst the Piranha species. There appears to be little appetite (pun intended) to own these fish. Each has a different set of characteristics as well as behaviours, but most people want to own the ‘true Piranha’, The ones with teeth.

Amongst many Piranha owners, the Red-Bellied is considered both affordable and hardy for a beginner. They are quite simple to look after and look quite stunning one their red bellies start to show.

The Red-Bellied Piranha are also quite easy to source, and there are plenty of sellers. The more exotic you go, the harder they are to find and the more expensive they seem to be.

The conclusion is that unless there is a very good reason. The Red-Bellied Piranha is the one to own. It looks good, has a good reputation and are cheap to obtain. They also do not grow to ridiculous sizes in captivity.

What Are The Water Demands For Piranha?

The whitewater pH of the Amazon river is 6.9, so if you recreated that in your aquarium your Piranha fish would be fine. Certain parts of the Amazon are said to be slightly more acidic in nature.

Most of the Red-Bellied Piranha in pet stores are raised in a commercial environment, not caught from the Amazon, so are often used to water pH’s slightly higher, just into the alkaline range.

In truth, Piranha will survive in water with a pH between 5.5 and 8.0, but extremes should be avoided. The water temperature should be between 75° and 80° F (24 to 26.5 degrees Celsius).

If you live in a climate not conducive to keeping the water in this temperature range, then your aquarium will need a heater to keep the water optimal. The Amazon river fluctuates between 70° and 88° F (21 to 31 degrees Celsius). Water temperature falling will produce sick Piranha.

You will need to change 10% of the water weekly or around 25% monthly, and monitor the pH.

a piranha aquarium tank

Aquarium Demands for Piranha

When selecting a tank, almost consistently the advice is ‘as big as you can afford to maintain’. This is true for many fish, but particularly aggressive ones with teeth.

Fry or juvenile Piranha that are an inch long can obviously be kept in a small tank, maybe around the 20 gallon mark. But Piranha grow quite quickly so you will need to change tanks pretty soon after acquisition.

The correct way to think about Piranha aquariums is to get the right tank right from the beginning. Eventually 5 or 5 Red-Bellied Piranha will require a tank of 100 gallons at the very least. This maintains stress free fish that remain healthy, and not a fatality to the more dominant fish.

Obviously with fish that can produce an injury, a lid should be kept on the tank and the lighting should be subdued. Too bright a light will make your Piranha seek shelter in the tank away from the bright lights.

A light current is considered best, and as they are considered a messy fish, a good filter with the required capacity is considered best practice. Keeping the correct water conditions is a bit more of a challenge with Piranha.

Think carefully about the tank before you buy Piranha. They can live for around 10 to 15 years in captivity quite easily which is no small commitment to make. A good pet store will normally re-home Piranha if you can no longer care for them but it shouldn’t be done on a whim.

The Piranha Aquarium – What You Need To Know

The Piranha’s Natural Habitat – A Brief Overview

All species of Piranha are indeginous to the Amazon basin in Latin America. They only exist outside this region in captivity in controlled conditions. Most species are found in the Amazon river itself so they thrive best in clean water with a mild current. They are rather shy in nature so an aquarium needs plenty of hiding and ambush places for the Piranha to retreat from. Some darker areas are best so the Piranha can hide away from bright sunlight if needed.

What’s The Correct Piranha Tank Size?

While a small 30 gallon tank is OK for juvenile or fry Piranha, when buying a tank you should consider the fact that they can grow quite quickly and best practice is to buy the tank that your Piranha will grow into.

If you are going to keep Red-Bellied Piranha, they are a schooling fish so you will need 3 or more. They naturally form schools for protection and the rough rule of thumb is a 60 gallon tank for 3 or 4 fish and then an extra 20 gallons per additional fish.

Thus 5 fish should be a 100 gallon tank (60+20+20), although you could get away with around 80 gallons. There are no hard rules, these are just recommended guidelines.

The more Piranha you keep in a tank, the more imperative it becomes to keep them well fed. A Piranha growing hungry has a tendency towards cannibalism if they are left to their own devices. The more Piranha you try to ‘cram in there’, the more likely you are to lose one of the Piranha.

It’s much better to give them the space and respect they deserve.

a red bellied piranha

Water Conditions (Temperature, pH)

Their natural conditions will be the conditions of the Amazon river.  Piranha do particularly well in clean and tropical water. The water temperature should be between 75°F to 80°F (24 to 26.5 degrees Celsius), with the pH between 5.5 and 8.0.

Keeping the water clean becomes paramount when you consider that they are quite messy eaters. Food in the water can get shredded and a lot of ‘debris’ may result. Thus, powerful filtration systems are a good idea to keep the water clean.


In nature the Piranha are not an ‘open water’ fish. Naturally they will find places to hide for protection. In a tank, you want them to follow this instinct but not remain permanently out of sight.

Live plants like hornwort, javamoss and ferns have worked well with plenty of areas where they can escape to, with overhead protection and darker areas to retreat to.

Make sure the tank is not overcrowded though, and there are open swimming areas for your Piranha swim freely. When feeding, Piranha require open water to eat without fear of injury from a nearby rock or decoration. If attacking another fish, there should be an area of the tank that allows them to use their power and speed in open water.

Piranha can be particularly affected by strong sunlight, so aquarium lighting should not be too bright. Provide your fish a shaded area out of direct sunlight, where they can retreat to if there is too much light. If your Piranha are there permanently, it might be a good indication that the lighting is too strong.

What Foods to Feed Your Piranha?

Contrary to popular belief, Piranha are not carnivores. They are, in fact, omnivores. In their natural habitat they survive on a diet of fruit, seeds, insects, worms, plant matter, crustaceans and other fish.

In captivity, in a home aquarium they should be given things that replicate their natural diet. They can and do eat other fish, but the diet can be replicated without the need to feed them live fish, which is in fact, not recommended.

The people that do want to feed their Piranha fish, such as a seperate tank with goldfish in it can end up with a very messy tank as the whole fish is not consumed.

To satisfy their carnivorous desires you can feed them frozen fish, like shrimp, as well as pieces of meat. The risk is that other fish can sometimes carry diseases and parasites not conducive to your Piranhas health.

Typically, Piranha will not like the kind of fish food that goldfish will eat, that is flakes. They may, but it would not be normal. It’s certainly something to try, though.

To keep your Piranha healthy with a balanced diet, you should feed them shrimps, frozen fish, crustaceans, fruit, worms, and vegetables like potatoes or zucchini. This gives a natural balanced diet like they would receive in the wild.

In the wild they take whatever comes along, including nuts and seeds. It’s not recommended you overfeed Piranha animal meats as that is an irregular meal, and can cause problems if repeated often. A balanced diet is the best choice. Piranha cannot metabolize most animal product meats.

It’s also recommended to only feed them what they can consume in a few minutes. After they have done feeding remove the uneaten foods to keep the water clean and prevent rotting food.

Also, keep an eye out for each Piranha. If you have more than one in the tank, make sure they are all getting a good share. Essentially, make sure they are all fed well. A hungry Piranha is not something you want in your tank.

Piranhas are not typically fussy eaters. If there is a good food source they will consume it. There are a large variety of foods that can be purchased, or indeed kept from your own meals that can feed your Piranha.

Breeders, however, avoid using live fish due to the risk of contamination and disease. The best meats are poultry meats, worms, insects, shrimp and frozen fish.These are nearly always parasite free and therefore healthy to your Piranha. Another option in meat based pellet foods, if your Piranha seem to like them. They last longer, as they are a dried food source and for the cost conscious, pretty cheap too.

Piranha Food and Taking Care Of It:

As your Piranha will eat almost anything, it is largely up to you to provide it the varied diet it will need. Frozen fish is a good alternative to feeding a Piranha a live fish. Much healthier, less messy and with lower risk.

Oddly, in the wild it is normally eyes, fin nips and scales that Piranha end up eating. A good quality processed frozen food is a good alternative. As opportunistic feeder in the Amazon river, occasionally a carcass will drift down the river and be eaten by Piranha, but it is not common, which is why humans deaths are always exaggerated by the media.

The goal should always be to replicate the varied diet a Piranha will naturally encounter in the wild. If you can do this, then you are well on your way to keeping healthy Piranha.

As it happens, goldfish are not considered particularly nutritious. While the idea is interesting, own Piranha and feed them fish, it isn’t the wisest decision. In fact, it’s a good way to risk killing off your Piranha.

As they are growing, around the fry stage, and into juvenile statues, you can feed your Piranha a few times a day. Eventually though, you should feed them once a day, with whatever they can consume in 3 minutes. Keep feeding them small amounts of food for 3 minutes, then stop and clean away the remaining food if there is any.

This prevents overfeeding, and prompts healthy Piranha. There is no reason why your Piranha won’t last 15 years in your care.

As your Piranha feed on their meals, they will acutely be aware that they are vulnerable to being prey. This is an instinct, so you will need to provide cover to satisfy their needs. They are considered a shy and timid fish, rather ironically.

To create their stress free environment, you will need to provide shelter and cover for your Piranha. In the wild, they will mix with the river plants and rocks in order to feel more secure from attack. In a tank, the desire to do this will need you to provide this kind environment, making sure there are not sharp rocks so in the event of them being startled and diving for cover they are not accidentally injured.

Depending upon their environment, you might want to experiment with how to lay the tank out. You should provide enough cover for the amount of fish you possess. Yet, there should be free runs to swim cleanly in the current and spacious feeding areas. Typically, around 50% cover would be acceptable.

Sufficient and effective cover reduces stress in your Piranha so it should not be an afterthought. If you use live plants, be aware that Piranha will consume plant matter.

Equipment for Piranha and Upkeep:

Keeping healthy Piranha isn’t too difficult but it does require a serious commitment. They’re not goldfish in a tiny bowl, that can survive of flakes. As well as a large spacious tank, clean water with a mild current in a water temperature suitable for their development, you will need to keep abreast of their development and needs.

Clean and flowing water can be achieved in an aquarium but it does take knowledge to make happen. Certainly Piranha do live naturally in stillwater, but a mild current also helps keep fish healthy.

Water temperature is paramount as you need to replicate the Latin American conditions for them to survive. Between 76° and 83° F is considered fine for their health. The temperature does need to be monitored through, so some sort of tank thermometer is highly recommended.

Variations above and below the extremes can cause problems, mainly by damaging the immune system.

If the water is raised well above the 80° F level, say 88° F and beyond the following effects may be observed


  • Oxygen deprivation, causing nerve damage
  • Pulmonary damage (heart beats faster to get oxygen)
  • Reduced immune system


Keeping them in water colder than 70° F starts to chill the fish and the effects of cold further reduce an immune system.

As the immune system becomes damaged, the Piranha become more susceptible to disease, such as

Ich: Also known as white spot disease, it is a parasite that you may have to deal with anyway. It is very common to home aquarium enthusiasts and is responsible for a great many fish deaths. It normally arises in stressed fish caused by proximity to one another. It is treatable.

Dropsy: It is a condition where the belly of the fish may become swollen, caused by infectious bacteria in the aquarium. It is particularly prevalent when a fish is stressed. Skin lesions may appear, but it can also damage the internal organs and can prove fatal.

Mouthrot: A bacterial infection of the mouth, also known as cotton mouth or cotton wool disease, Diagnosed by white cotton wool like growths on the mouth, your Piranha will not feed and thus lose weight.

As well as keeping the water fresh and clean, it is recommended that weekly 10 to 15% water changes are performed. As well as an efficient water filter, this ensures the stress free environment to keep the immune system of your Piranha healthy.

You can probably see why a large tank for Piranha is recommended now.

Good filtration is key to a healthy tank. Make sure when you are selecting a good filtration system that it is appropriate for a large tank.

a single red bellied piranha

Lone Piranhas And Prospective Companions

If you have made, or indeed are in the process of making the decision to keep Piranha for pets, then one of the attractive qualities, apart from the unusual nature would be their particular brand of aggressiveness as a predator.

They can, in certain circumstances, like when they are feeling threatened or with extreme hunger be prone to attacking whomever is causing their problem. In the wild, that is normally other fish. Sometimes, it is cannibalism.

Thus it is not recommended that you keep other types of fish in the tank, along with any Piranha. If you want to keep other species of fish, it is better to have another tank, especially if they are valuable.

With respect to companion for Piranha, you are generally talking about other fish from the same genus.

The Pygocentrus genus of fish, to which the Red-Bellied Piranha are classified in, are considered schooling fish, so you will want 3 or 4 (at least) fish to keep Red-Bellied Piranha company. They are not used to being on their own, and in pairs may fight for dominance.

Piranha from the Serrasalmus genus, such as the black Piranha, are quite the opposite in nature. They are solo fish. They swim, travel and feed alone. They are particularly aggressive towards any other fish, including other black Piranha. In addition, the black Piranha has the most powerful bite of all the Piranha, so it makes to take note of that fact.

Locating The Aquarium

Whilst goldfish are quite happy in a bowl, the fact that Piranha need a bit of space as they grow to 10 inches in length, shoal with 3 or 4 fish means that a tank has to be a good size. At least 60 gallons is recommended as a rule of thumb.

Couple this with them being a shy, timid fish that prefer low lighting, means you need to think carefully about where to place your aquarium. Finding the right spot in your home, means trying to alleviate the problems you may encounter.

There are no hard and fast rules to this, but they need to be in a place where the water temperature can be maintained, and many people will not move past. They also need to be out of direct sunlight, with low subdued lighting.

Where that is in your home, only you know.

Piranha Treatment and Upkeep

Once you have the basics under your grasp, Piranha become rather easy to keep. They are not a particularly demanding fish, and with a healthy diet, a good environment with clean water they are a pretty hardy fish.

General maintenance is pretty much the same as any other fish, although if you want to clean the water its recommended you remove them from the tank first. No hands should be in the water, despite the fact that the risk of a bite is low.

If you remember that they are messy eaters, and filtration will need regular upkeep then you shouldn’t find Piranha too hard to keep.

Piranha Behaviour In A Tank

With respect to the Pygocentrus genus, such as the Red-Bellied Piranha, from the time you put them in the tank as young fry, they have a tendency to school. It seems instinctive for them to try and protect themselves.

Into adulthood, they move into small groups. In the wild it may be around 20 or so. Single and paired Piranha do not act very naturally normally. They can look rather shy and timid. Your prized Piranha can skulk within protective decorations you have provided for them.

You should never really place your hand in the tank unprotected but even if you did there is little chance of being bitten if they are well fed. They will most likely hide under decorations, or in the corner at the other end of the tank if you have a hand in the water. They will only attack under hunger, or in this case if they feel threatened.

When setting up your tank, it’s almost always best to introduce them to the tank as juveniles as they get used to the procedures performed from an early age. If and when you have to remove them, remember those teeth are razor sharp, which is bad news for the net you may use to change tanks temporarily. Get a proper net, suitable for Piranha.

Red Bellied Piranha in a home aquarium

Piranha Tank Mates

General Behavior

Left to their own devices, a school of Piranha in a healthy tank will find a quiet protected little spot and swim gently against the current. However, if anything is introduced into their environment, they become a lot more alert. They will instantly try to analyse whether it is a threat or whether it is prey. The fight or flight response begins to work.

Piranha can be aggressive predators, and if they feel threatened they will use their power and teeth to protect themselves. A school will act as one, each fish trying analyse the correct response to the unknown.

Piranha should be introduced to the tank in similar levels of development, adding a juvenile Piranha to a tank full of adults, often does not go too well. A large tank reduces stress, and allows each fish their space if they need it.

A Red-Bellied Piranha will display vivid colors, and glistening eyes if it is healthy and stress free. Interestingly, a sign they may be hungry is light chomping of the mouth. If you see this and haven’t fed them for a while, it’s a good idea to feed them right away.

With a hungry Piranha, the other fish in the tank are in danger. Fin nipping is common if they are not fed.

With schooling Piranha in a tank, you may witness signs of dominance and displeasure, which rather remarkably looks similar to the breeding signs.

Circling the tank, wagging tails and dipped heads with tails slightly raised are signs off displeasure and aggression. Piranha as a first strike go for eyes and fins of another fish.

How to Maintain Healthy Piranha

It seems easy to say, but the very best conditions are the way to keep your Piranha happy and healthy, living as stress free environment as possible.

Not introducing parasites to the environment via feeder fish is also another way to keep the risk of disease away. Diseases on feeder fish will likely transfer to your Piranha if they are unhealthy. If you browse youtube for long enough, there are a few people who are feeding live fish to Piranha, but this is not recommended for the serious Piranha owner.

A powerful filtration system to keep the water free from debris and disease is also a good way to maintain the health of your fish. Along with regular, weekly water changes to make sure rotting food doesn’t contaminate the tank, along with Piranha ‘waste’.

Piranha Breeding

Obviously it would be difficult to breed black Piranha, as you are meant to keep these fish on their own in the tank. Breeding black Piranha is probably best left for zoos and professional breeders.

However, schooling Piranha, like the Red-Bellied Piranha, it might be possible if you have a mix of males and females in your tank. Prior to breeding they turn slightly ‘blackish’ and may move to be nearer to plants. Piranhas build nests, and if there is vegetation in the tank, you could well see Piranha eggs on the stems.

Male vs Female Piranha

Telling the difference between male and female Piranha is very difficult. With most species the distinction between the sexes is quite obvious. With Red-Bellied Piranha, the difference stems from their belly regions.

With younger Red-Bellied Piranha, both sexes are a silvery fish, without their trademark belly coloring. As it happens, as the fish age, that red belly can discolor as well. Only when they are adults is there a distinct red belly to these Piranha.

The common way to tell is that the males have a ‘markedly more pronounced’ red belly, which is somewhat more heightened during the reproductive phase. Female Red-Bellies can have a slightly yellow tinge to theirs.

The female abdomen is slightly more rounded as well.

Red Bellied Piranha in a home aquarium

In Theory, How Would You Breed Piranha?

You may not be intending this to happen but if you have a 100 gallon tanks with 6 Red-Bellied Piranha in it, and you have managed to get some males and females in their, there is a good chance you might have to deal with breeding Piranha.

Red-Bellied Piranha, that are based in a home aquarium may show signs of breeding behaviour after 10 months, when they will be 5 to 6 inches in length. A full Red-Bellied male will ‘pair’ with a female. The female might display a slightly more yellowish belly.

This will only happen if the Piranha are stress free, and healthy. In practice this means a large tank, without being overpopulated, with clean freshwater, at the required temperature and pH.

Piranha build nests, so a small gravel bottom will be conducive to breeding.

The school may dissipate somewhat and you start to see more pairing happening. The male and female, together will build a nest near plant vegetation. It’s said that raising the water temperature towards the upper end of the range has beneficial effects on breeding.

At the start of spawning the male Red-Bellied Piranha makes a nest by making a hollow in the gravel on the bottom of the tank. The female will remain nearby.

The female fish then lays her eggs and the male fertilizes them. You should expect between 500 to 1500 eggs.

Unusually for any fish, but completely contrary to their reputation, the Piranha then guards the nest. In the wild, this is often when bites occur. People in the water treading near Piranha nests.

Piranha eggs turn into larvae within a few days, and within 10 days you may have very juvenile Piranha swimming around.

At this point it is worth considering removing them from the tank.

Red Bellied Piranha in a home aquarium

Conclusion – Are Piranha Right For You?

Whilst it sometimes seems there is a lot of information to digest, if you are looking for a wildly different pet to keep, that makes conversation wherever you go, then considering Piranha is a good choice.

That interest though, comes with an implied responsibility.

They are not a worm farm, they are living fish that have very specific requirements to keep them healthy and stress free. Striving to keep them healthy should be your ultimate goal.

Successfully keeping and watching Piranha grow from the tiniest little fish to a 12 inch adult is both a fascinating and rewarding endeavour.

You must make sure that keeping Piranha is legal where you are based. Check with local authorities. You might just need a license and permit.

You must be prepared to feed them daily a varied diet of both plant based matter, fruits and frozen meats to keep their immune system healthy. You must also clean the tank weekly, and remove 10 to 15% of the water to make the environment the very best you can.

With all that done, adult Red-Bellied piranha can live up to 15 years so you must be prepared to commit a significant portion of your time to your new hobby.

Despite being shy and timid, contrary to their reputation they are still one of the most exciting fish you can own. Watching several Red-Bellied Piranha tear into chicken meat, and take turns in a coordinated attack bring a little of natures natural drama to your home.

Ultimately though you must look after those in the household. At times, and with the right conditions never forget these are an aggressive fish, particularly if they are hungry, threatened or are near breeding. As well as keeping your Piranha healthy and free from disease, you must also guard against injury to those who treat your pet Piranha with a lack of respect, a respect they both should have and deserve.


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