Now that I’ve gone through most of the basics about owning pet piranhas, which mostly covered our friendly neighborhood red belly piranha as a starting point, I thought it was high time that I start showing off the other piranha bad boys. There are a lot to cover, so please bear with me… it might take some time. Today I’m going to cover the Black Piranha.


The Black piranha has been known by many names over the years. Here’s a list of all the ones I could find:

  • Serrasalmus rhombeus (redeye piranha)
  • Serrasalmus spilopleura (speckled piranha)
  • Rhombeus Piranha
  • Caribe ojo rojo (local name)
  • Caribe amarillo

You also have the Jet Black Highbacks or Peruvian Black Piranhas (for Peruvian S. rhombeus), which are more on the greyish side, and the Brazilian Black Piranhas which are also on the greyish side. Unfortunately, I had a hard time finding images to show the difference. If any of you have one, please send them my way!

Piranha Red Bellied Tropical Tank Fish Aquarium
Piranha Red Bellied Tropical Tank Fish Aquarium

Cool Characteristics

    • Just like most piranhas, it is usually found in South America, in Amazon River basins. Although, from time to time one can be found in a local lake in the States because someone decided they didn’t want to take care of it anymore. (Tsk, tsk, tsk!)
    • This one is not the easiest to identify when they are young, however when they get older, their color usually becomes a dark grey/black and their eyes become freakishly red. The more common ones you will see are diamond-shaped.
    • This one is a bit of an introvert. He’s quite shy and likes to be kept alone for the most part so most aquarists will keep them solo.
    • The black piranha has a chomper as strong as 25-30 times his body weight. So if one happens to get a hold of a finger or hand, consider it gone or at least unusable for the foreseeable future.
    • Black piranhas in captivity can grow up to 16-18 inches in length, while the wild ones have been known to grow easily over 20 inches.

Nothing beats a few videos to see what piranhas look like in the flesh, so please have a look at these two. The first is a black piranha in captivity and the other in the wild.

Aquarium Specifics

Size and Decor

Like I mentioned above, these persnickety creatures can grow pretty big so you will need a big aquarium to handle them if you want them to have room to swim around and stay healthy. You’ll find all sorts of recommendations on the Web so determining the right size is a tough one. Since black piranhas grow slowly, you can get away with a 40-55 gallon tank for a year or so, but once they reach full length, I wouldn’t go for anything under 75 gallons, and preferably 100 gallons if you can afford it. So unless you want to switch mid-way through, you might as well go for the bigger one right away to save you the headaches.

As for the décor, make sure the big guy has a few places to hide. Like I said above, they are a little bit on the shy side and they’ll feel more at home when they can hide a bit. Have a good mix of large rocks, some driftwood and floating plants and you should be good to go.

Water conditions

Just like any other piranha, the Serrasalmus rhombeus does not like bright lighting, so try to keep it to a minimum if you can. As for water chemistry, I would keep the levels at about here:

  • – Temperature: 75 to 82 degrees
  • – pH: 5.8 to 6.8

Tank Mates?

Personally, I wouldn’t recommend it. (Unless you plan on breeding them of course, but I’m not covering that today since that his a WHOLE other topic which unfortunately I have no experience with). Seriously though, most tank mates will end up being lunch (or maybe an appetizer depending on their size), so you are better off not taking a chance.


The black piranha isn’t much different, other than most black piranha owners skip the non-meat section since black piranhas are massive carnivores. So stick with the meaty suggestions and you’ll do just fine.If this is the first time you are venturing into the world of piranhas, I’m not sure the black piranha is your best bet. They are more expensive that the average pet piranha and because of its size, it usually means you shelling out more dough ($) for a bigger aquarium, accessories, etc. I’m not trying to discourage you; I’m just saying it like it is.