How to Care for Piranhas

Co-authored by Doug Ludemann

Last Updated: December 6, 2024 Approved

A piranha is a member of a family of omnivorous and predatory freshwater fish which live in South American rivers.^{[1]
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Research source} Because these fish often spend their time looking for prey, many people associate piranhas with sharp teeth and an aggressive appetite for meat. But never fear, piranhas are unlikely to attack humans and large animals unless they feel threatened or trapped, or are starving. By properly setting up a tank and tending to the fish, you can care for and enjoy piranhas as pets.

Things You Should Know

Buy an aquarium that will suit your number of fish, choose a secluded location with low light, fill it with water, and finally, include decorations that offer the fish privacy.
To keep your piranhas healthy, regularly clean your aquarium by replacing its water, testing the water quality, and checking your water filters.
In addition to feeding your piranhas once a day, keep them healthy by looking out for signs of illness and unusual behavior.

Part 1

Part 1 of 3:

Setting Up A Tank

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Get an aquarium. A proper habitat is key to caring for your piranha, so create a home as close to the fish’s natural habitat as possible.^{[2]
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Expert Source

Doug Ludemann
Aquarium Care Professional

Expert Interview. 27 August 2019.} Many people suggest getting a tank large enough for 4 piranhas to best mimic the natural environment. However, you may want less. Get an aquarium of at least 25 gallons for one piranha or 60 gallons for four piranhas to properly house them.^{[3]
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- Buy a tank that corresponds with the number of piranhas you’ll have. For example, if only want two animals, a 40 gallon tank should be enough space for them. As a rule of thumb, you want about 20 gallons of water per animal or 60 gallons for 4 piranhas.^{[4]
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  Research source} Make sure to the biggest tank you can afford so that your piranhas can flourish. If you’re trying to save money, consider a second hand tank. Wash any tanks before introducing your piranhas to them.
- Consider getting an optional tank screen for the top. Piranhas can jump and injure their owners if they’re hungry. You also want to ensure that pets or small children don’t fall in the tank.
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Find an appropriate spot for the tank. Piranhas are messy animals that are also surprisingly timid.^{[5]
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Research source} In addition, direct sunlight or heat can encourage the growth of bacteria that can harm your piranha. Placing the tank in a spot that is not exposed to extreme heat or lots of traffic can keep your piranha happy and healthy.^{[6]
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- Put the tank in a place with a relatively consistent temperature of 75 to 80 degrees Fahrenheit (21 to 25 Celsius). Attach a thermometer to the aquarium to monitor the temperature. You shouldn’t put the tank anywhere it may get direct sunlight or be exposed to radiators or heating devices.
- Find a low-traffic space in which to put the tank. If there are too many people walking by the tank, it can stress out piranhas and may make them aggressive.
- Consider putting the tank in a space with low light. In the wild, piranhas live in murky water that is under the canopy of the rain forest so their eyes have adapted to dimmer lighting.
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3
Fill the tank with water. Piranhas are surprisingly hearty fish and can adapt to different water conditions. In general, they live in warm, fresh water between 75 to 80 degrees Fahrenheit. They also thrive at a pH of 5.5-8.0.^{[7]
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Research source} You can fill the tank with warm tap water as long as you’re using several filters in the water. In addition, you should keep a temperature in the water to ensure it is optimal for your piranhas to thrive.
- Add several small filters to the water or one very powerful external filter to keep the water clean.
- Consider getting a heater for the water to keep the water a consistent temperature.^{[8]
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Add hiding spots.^{[9]
X
Expert Source

Doug Ludemann
Aquarium Care Professional

Expert Interview. 27 August 2019.} Because piranhas are shy, they like to hide. Putting some decorations in the tank can help keep your piranhas happy and healthy.^{[10]
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- Decorate the tank with live and plastic plants as well as smooth gravel, and pieces of wood. Be aware that Piranhas may destroy live plants. A clean piece of PVC piping can also provide piranhas a place to hide if they feel stressed.^{[11]
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- Choose decorations that you like. You can use live or plastic plants or a combination. If you’re using live plants, consider hardy, low-light options such as hornwort, java moss, or fern. Any type of plastic plant you like will work.
- Soak any wood or driftwood in a tub or bin until it turns a brownish color. Many piranhas like the dark color of the water, but it may be difficult to see your fish. Make sure the driftwood fits in the tank and gives your piranhas plenty of space to swim freely.
- Use smooth rocks and gravel that only barely cover the bottom of the aquarium. You can safely use granite, basalt, gneiss, slate, and quartz. Avoid limestone, marble, dolomite, calcareous sandstones, chalky rocks as well as corals and sea shells. All of these can upset the pH of the tank.
- Place as many decorations as you like in the tank, but remember that your piranhas should be able to swim freely without hindrance. A good rule of thumb is 50-75% coverage in the tank to make your piranhas feel comfortable. Too many decorations can also more quickly decrease the water quality.

Part 2

Part 2 of 3:

Cleaning the Tank

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Clean the tank weekly. Fresh and clean water is an absolute must to your piranha’s health. Replacing 10-20% of the water every week and cleaning tank walls and gravel can prevent a compromised immune system and also odor. Weekly maintenance shouldn’t take more than 10 minutes.^{[12]
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- Write a schedule for yourself to clean the water at the same time each week so that you don’t forget. Clean the aquarium more often if you notice excess waste—remember piranhas are messy—or odor.^{[13]
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  Expert Source
  
  Doug Ludemann
  Aquarium Care Professional
  
  Expert Interview. 27 August 2019.}
- Be aware that you shouldn’t remove your piranhas from the tank if at all possible. Remember that piranhas generally attack when they feel threatened or are hungry. Protect your hands with a pair of heavy gloves when cleaning. If you absolutely have to remove your piranha from the water, place a bucket or large fish net in the tank and quickly place your piranha in a separate tank.
- Use a water changing device, or python, from a local pet store for best results.^{[14]
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  Expert Source
  
  Doug Ludemann
  Aquarium Care Professional
  
  Expert Interview. 27 August 2019.} These hook up to a sink and make it easy to clean the tank. This can also minimize the risk of your piranha becoming aggressive with you.^{[15]
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  Research source} If you don’t have a water changing device, gently remove each piranha and put them in a separate holding tank while you clean. This will allow you to clean the tank without stressing your fish or getting injured because the piranhas are stressed.
- Vacuum the gravel and remove any waste while using the water changing device or when the tank water is low and no piranhas are in the tank.
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Maintain high water quality. The health and lifespan of your piranha is dependent on high water quality. Ensure proper pH and oxygenation by testing the tank water after every cleaning.^{[16]
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- Test tank water with a test kit that you can get at large retailers and pet stores. Test to figure out potential problems like low oxygen, high ammonia, and acidity.^{[17]
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- Fix any problems with the water. The pH level can range from 5.5-8.0. Use a chemical neutralizer to restore the pH levels if they are off. Oxygen saturation should exceed 70%. If it doesn’t, you may need to replace your filter or filters.^{[18]
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  Expert Source
  
  Doug Ludemann
  Aquarium Care Professional
  
  Expert Interview. 27 August 2019.}
- Use a thermometer to make sure the temperature is between 75 and 80 degrees Fahrenheit. If necessary, turn up the heater until you reach the optimal temperature range.
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Check the filters. Piranhas produce a lot of waste, which can also affect the water quality. Make sure you have a very strong filter or several small filters to stagger maintenance. If tank water gets dirty quickly, consider replacing your filters.^{[19]
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- Smell the water to see if it has a foul odor. This is a good sign you need to change the filters.

Part 3

Part 3 of 3:

Caring for Your Piranhas

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Feed your piranhas. Despite what many people think, piranhas are omnivores that eat everything, not just meat. Giving your piranhas a varied diet can increase their span and boost their immunity.
- Feed your piranhas once a day. Feeding them more often can lead to overfeeding and increases the amount of waste in the tank. Good live foods are guppies and minnows. Piranhas will not usually eat characins as they are a characin themselves. Piranhas should eat everything given to them within two minutes or this can contribute to poor water quality and susceptible to disease. The only exception is vegetables, which can be left for a few hours.
- Give your piranhas processed, frozen, and freeze dried foods including fish, crabs, prawns, rainworms and shed snakeskin. Occasionally feed them green vegetables such as raw zucchini, spinach, or potato. Avoid giving piranhas dry market feed, flakes or granules.^{[20]
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- Avoid feeding piranhas live animals. Not only can they introduce disease to your piranhas, but can contribute significantly to waste in the tank.
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Look for illness. Even though piranhas are hearty animals, they can get sick. Not maintaining the tank water and aggressive other fish can lead to illness and death. Piranhas should be active, alert, and have no body damage. Minor nipped fins are normal for a piranha. They should also eat readily and quickly. Watch each of your piranhas for any of the following signs of illness:
- Lethargy or sluggishness
- Unwillingness to eat
- Severe body damage such as bites or chunks of missing flesh
- Cloudy or missing eyes
- Labored breathing
- Visible parasites on the skin^{[21]
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Recognize normal piranha behavior. Piranhas are very complex animals that can exhibit a variety of behaviors that may not appear normal to you. It’s important to watch your piranhas to help you understand their behavior for cleaning the tank as well as watching for potential illness. The following are normal piranha behaviors that you may recognize:^{[22]
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- Aiming towards gravel and tilting the tail, both of which are signs of aggression to keep someone from entering the piranhas space
- Growing paler in appearance, which can be due to the colors not coming out yet or as a sign of stress
- Turning on their sides and rubbing the gravel to itch themselves, which can indicate poor water quality, infection, or just needing to scratch
- Holding their mouths open and wagging violently from side to side, which is a sign of the piranha being ready to fight
- Chomping mouths repeatedly, which is a sign of hunger
- Circling the tank repeatedly as a sign of displeasure with something in the tank or controlling the territory
- Intensify colors, which are a sign of the piranha being very happy or angry
- Turning black, which is a sign that a piranha is ready to breed
- Getting side by side and wagging tails, which is a sign that piranhas are breeding or ready to fight
- Biting each others’ fins as a warning to desist or be killed

Community Q&A

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Question

How many piranhas can I put in a 5 gallon tank?

Community Answer

None, that would be like having your entire home be a broom closet. It's best to get at least a 30+ gallon tank for one.

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Can they live in a ten or twenty gallon tank?

Benjamin Y. Jackson

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When finding a habitat for piranhas, bigger is always better.

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Where can I buy piranhas?

Daniel Hu

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Check your local petstore. Some places have laws that make it illegal to keep piranhas, so be careful and check the local laws before purchasing one.

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Tips

Piranhas are relatively easy to keep alive, but can get to be large and can live for 10-20 years.^{[23]
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Research source} Be prepared to pay for their large appetite, size requirements, and other needs.

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Remember that the more piranhas you have, the more often you will need to clean the water.

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Warnings

Piranha can be dangerous, so handle them with care and don't allow small children to handle the fish. If you are new to having a piranha, ask your local pet store or fish expert about best handling practices.

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