Aquarium Fish

Red Belly Pacu

The Red Belly Pacu fish looks very similar and is sometimes sold to customers as the Red Belly Piranha. However, Red Belly Pacu only look like piranha as juveniles. The red belly pacu will grow rather quickly and may reach 12 - 24 inches (30 - 61 cm) if properly taken care of. Given their potential adult size you will need an enormous tank to keep one at home, at least 250 gallons (940 liters). You will also need an extremely efficient aquarium filter to filter the tank water.

The Red Belly Pacu will accept flake foods in the home aquarium but will need to be given pellets as they grow in size. It's probably best to keep them in tanks without live plants because they may eat your live plants.

Use caution when selecting tank mates for this fish. Even though they are herbivores, they may go after smaller fish in their tank. They can potentially be kept with arowanas and plecos.

The Red Bellied Pacu one of those fish that is best left to the advanced freshwater aquarist with a very large tank.

Red Belly Pacu Picture

Red Belly Pacu Piaractus brachypomum
Photo Credit: Debra Mayo

Pacu Video

Red Belly Pacu Care

Scientific Name : Piaractus brachypomum

Common Names : Red Pacu

Red Pacu Care Level : Moderate - Difficult (because of adult size) and they need an excellent aquarium filter.

Size : 12 - 24 inches (30 - 61 cm)

pH : 6.5 - 7.5

Temperature : 75°F - 80°F (24°C - 27°C)

Red Belly Pacu Lifespan : 5 - 15 years or longer.

Origin / Habitat : South America, Amazon River

Red Belly Pacu Temperament / Behavior : Generally peaceful and will take care of themselves against more aggressive tank mates. They may also eat smaller fish species if kept in the same tank.

Red Belly Pacu Breeding : Egglayer, not common in home aquariums.

Aquarium Size : 250 gallon (946 liters) minimum but preferably much larger tanks and ponds. This fish is best left in the wild or in public aquarium displays.

Red Belly Pacu Tank Mates : Because of their huge adult size there are very few common aquarium species recommended. You would need to keep them with large fish making the aquarium size requirements difficult to attain in the home. One that may potentially be kept with them is the Common Pleco but you would need at minimum a 350 gallon tank to provide both of them with adequate water volume as adults. Arowanas are sometimes kept in the same tank as well (must be a huge tank). Sometimes sold mistakenly as the Red Belly Piranha.

Fish Disease : Freshwater Fish Disease

Diet / Foods : An herbivore - provide a varied diet with pellet food and frozen food. They do develop teeth.

Tank Region : Mostly middle

Gender : Difficult to determine. May only be possible to determine gender differences in mature adult Red Belly Pacu. Males may have more red on the belly.

Similar Species : Characins

Fish Lore Forum : Pacu Forum

Author : Mike FishLore


Red Belly Pacu Tips

From: Ray
I bought two red belly pacu from the pet store at about the size of a quarter. Not knowing there potential for growth I placed them in a fifty gallon tank. They are 30 cm long each now in under a years time. A truly beautiful pair. I feed them cucumber, and lettuce and they love it. Definitely listen to what people say these fish have the potential for being tank busters, and boy can they jump. I would definitely recommend starting with at least a hundred and fifty gallon tank if you plan on raising more than one of these amazing fish.

From: Lois
My husband also bought two at Walmart the size of a quarter about 7 months ago and they are now both approx. 8" long! They have outgrown the 20 gal tank; we moved them to a 30 and now bought a bigger tank. They grew up with other fish as we did not know they would eat other fish and everything was fine until the 7th month and then one Pacu started to nibble on some of the other fish. When we moved the Pacus, we bought 14 feeders and in 2 weeks only 4 remain. They also eat pellets. They won't eat veggies. They still wanted a few of the old tank mates and would not settle down until they where moved too! We love our Pacu's, they are beautiful, peaceful and graceful. I would love more if they were not so large. They are my favorite of all our fish!

From: Brenda
My husband also bought one from walmart! He is now about 18" long. We have him in a 150 gallon tank. Our pacu likes to be hand fed alge discs, so he can be pet. He loves to be touched. We also feed him zuchini and cucumber.

From: William
Bought my two pacus from a pet store about the size of a quarter. raised them in a 29 gallon hex and moved them to a 55 gallon show. They are now about 18 inches and the other 21 inches. They eat algae disk and pellets. They splash lots of water when the play with each other and their tank mate is an oscar. It takes three filters to keep the water clean. Undergravel filter and two outside filters. Sometimes they are so calm and other times the spook very easy.
You need a much larger tank to keep these three fish. They are way too cramped in a 55 gallon tank.

From: Derrick
I bought my pacu at a local pet store, he was about 6 inches, so we started in a 25 gallon not knowing how big he was going to get and how fast! I have had him for almost 3 years now and he is huge! He absolutly loves pond pellets that you get for Koi fish and he also loves frozen cubed bloodworms, I have a multi stage filter canister that cycles 360 gallons per hour and a 2 stage filter that hangs on the tank to help with keeping the water clean and safe for him, but I still have to do water changes on the tank at least once a week or week and a half. I know with owning one for years, researching and askin professionals that you keep your tank tempature between 75 and 80 degrees F, your pH level should be 6.5 to 7.5, your Alkalinity (KH) should be moderate 80ppm, of coarse chlorine should be 0 ppm, your Total Hardness (GH) should stay around 75 to 100 ppm, your Nitrite (NO-2) should be 0 to 5 ppm, your Nitrate (NO-3) should be anywhere form 40 to 0ppm.

Now watch your fish closely, if it develops any sort of strange behavior or starts acting lethargic, check the water quality, you might need to adjust the chemical attributes of your tank. Pacu fish are also susceptible to Nitrite/Nitrate poisoning although it isn't common unless water changes are not preformed (10& to 15& bi weekly). If your Pacu is sitting just below the surface of the water and gulps for air then there may be high levels of Nitrite or Nitrate in your tank. If your Nitrate levels are above 40 ppm (parts per million) then its time for a water change, its the only way to remove these poisons from you tank.


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