Pacu identification
- Thread starter Scorpio99
- Start date
No expert. Black I would say....not a red belly which is most common.
Pacu are very fast growing and not so much aggressive as they are unpredictable. Sometimes theyre peaceful and other times they rip everything in the tank apart and kill fish. I had a 6" Pacu kill a 9" Goliath African Tiger Fish. Regardless, they really are only meant for large ponds or museum exhibits. They get around 50lbs and theyre thin fish which means all that weight gets transferred to height and length; Ive seen Black Pacu probably larger than 24" high and 30" long.
They are tank busters for sure!! Need 500 gallon tank pretty quick and a pond soon there after. Not a fish for the light hearted or walleted.
Those are definitely NOT black pacu.
DIFFERENCE BETWEEN RED BELLY AND BLACK PACU
There is a lot of confusion about pacu. Even scientific names are confusing. Red belly pacus are the most common. They used to be called Colossoma bidens. The classification is Piaractus brachypomum in all current literature. Another name is pirapitinga. They can get up to 3 feet in length and weigh up to 55 pounds. Juvenile red belly pacus usually have red chest and bellies. The red color usually fades, and adults resemble black pacu in coloration. This can make it confusing to a pacu owner. Our pacu had no red on them when we got them. I thought we had black pacu. I was wrong, and some one pointed it out to me on a fish forum.
Black pacu are far less common. Their scientific name is Colossoma macropomum. They are also called Tambaqui. One article I read said they can get 3 ½ feet and weigh 97 pounds. It gets extremely confusing when searching the internet on this subject, because some of the authors themselves get mixed up and post pictures of adult red belly pacu, when writing about black pacu. The similar coloration of adult red belly pacus throws even the authors off.
So how does a person figure out what kind of pacu they have? Fortunately for most of us, we have red belly pacu. Fortunate, because they don’t get as big as blacks. After you have seen pictures of black pacu you can see their difference from red bellies. Blacks have a more elongated oval look. Their heads are elongated. Here’s a couple of sites with pictures of black pacu.
https://www.flickr.com/photos/dave_irving/3749678082/
https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=418
http://www.seriouslyfish.com/species/colossoma-macropomum/
Besides the elongated pointed head and and oval body, what else distinguishes these two species? Red bellies have a more rounded head. They also have smaller adipose fins that lack rays. If you look at your pacu’s adipose fin, it will probably look like an extension of fish skin. The fin flops around from side to side depending on which way the tail is moving and the body is moving. Black pacu have adipose fins that are supported by bony spines known as rays. So if your pacu has an adipose fin that he can move around like his dorsal fin, you probably have a black pacu. The opercula is short on the red bellies as compared with the larger semi-lunate shaped opercula on the blacks.
https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=427
Red bellies have a second row of molars in their upper jaw, and blacks only have one row…but how many of us are going to be checking out their teeth…
Blacks have an oval shape, while red bellies are rhomboidal in shape.
http://www.acuteangling.com/…/gui…/tambaqui-pirapitinga.html
Armed with this information, you should be able to tell what kind of pacu you have.
JohnPTC's black pacu
My red belly pacu that I thought were black pacu because they were dark. Notice they are more rhomboid rather than elliptical in shape.
My red bellys have a slightly lighter coloration under their chins now.
DIFFERENCE BETWEEN RED BELLY AND BLACK PACU
There is a lot of confusion about pacu. Even scientific names are confusing. Red belly pacus are the most common. They used to be called Colossoma bidens. The classification is Piaractus brachypomum in all current literature. Another name is pirapitinga. They can get up to 3 feet in length and weigh up to 55 pounds. Juvenile red belly pacus usually have red chest and bellies. The red color usually fades, and adults resemble black pacu in coloration. This can make it confusing to a pacu owner. Our pacu had no red on them when we got them. I thought we had black pacu. I was wrong, and some one pointed it out to me on a fish forum.
Black pacu are far less common. Their scientific name is Colossoma macropomum. They are also called Tambaqui. One article I read said they can get 3 ½ feet and weigh 97 pounds. It gets extremely confusing when searching the internet on this subject, because some of the authors themselves get mixed up and post pictures of adult red belly pacu, when writing about black pacu. The similar coloration of adult red belly pacus throws even the authors off.
So how does a person figure out what kind of pacu they have? Fortunately for most of us, we have red belly pacu. Fortunate, because they don’t get as big as blacks. After you have seen pictures of black pacu you can see their difference from red bellies. Blacks have a more elongated oval look. Their heads are elongated. Here’s a couple of sites with pictures of black pacu.
https://www.flickr.com/photos/dave_irving/3749678082/
https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=418
http://www.seriouslyfish.com/species/colossoma-macropomum/
Besides the elongated pointed head and and oval body, what else distinguishes these two species? Red bellies have a more rounded head. They also have smaller adipose fins that lack rays. If you look at your pacu’s adipose fin, it will probably look like an extension of fish skin. The fin flops around from side to side depending on which way the tail is moving and the body is moving. Black pacu have adipose fins that are supported by bony spines known as rays. So if your pacu has an adipose fin that he can move around like his dorsal fin, you probably have a black pacu. The opercula is short on the red bellies as compared with the larger semi-lunate shaped opercula on the blacks.
https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=427
Red bellies have a second row of molars in their upper jaw, and blacks only have one row…but how many of us are going to be checking out their teeth…
Blacks have an oval shape, while red bellies are rhomboidal in shape.
http://www.acuteangling.com/…/gui…/tambaqui-pirapitinga.html
Armed with this information, you should be able to tell what kind of pacu you have.
JohnPTC's black pacu
My red belly pacu that I thought were black pacu because they were dark. Notice they are more rhomboid rather than elliptical in shape.
My red bellys have a slightly lighter coloration under their chins now.
