Our 7+1 pacu

[thebiggerthebetter]

Flashback from 2010-2011. Along with iridescent shark catfish (IDS), pacu have always been the most plentiful number-wise among our rescues. We probably rescued couple of dozen 1'-2' pacu in those years. They are also nasty, unacceptable tank mates for timid and relatively slow and large fish, such as IDS and other shy Pangasids, like the black ear, channel catfish and bullheads (Ictalurids), large Doradids, such as niger, granulated catfish, irwini catfish, soldier catfish, etc. They do ok with TSN and RTC and their hybrids, with paroon sharks and other aggressive or assertive tank mates.

We didn't know it back then when we started our rescue. Here they are in a 4000 gal basement pond, 40'x6'x3':



...

Back to 2017. Our current 7 pacu are in 4500 gal -

-- one albino about 2.5' long and ~1.5' tall; grew it up from a baby, got from snookn21 about 2.5 years ago
-- two are from Toyin, rescues, IDK the species - smaller ones with olive top and black bottom and fang-like skin flaps at the mouth
-- four are rescues from Gerber's Dayton, Ohio, Mar 2016 (got 7, 3 perished), were ~1'-1.5' in Mar 2016, very poor shape, mouth rot, thin, beat up; the biggest today is ~2' round disk

1 albino a rescue in 240 gal, still small, ~16"

Can someone proficient in pacu tell me the species of each kind - albino, Toyin's, and the four grey ones?

 

[AquaAlex1993]

The albino is a red belly pacu.
It looks like you have a few regular red belly pacus in there as well.
What I am not so sure about is a few of them look like Black Pacu and there there are a few that look like they could be yellow bellies. But I am not 100 percent certain.

 

[tlindsey]

I wish more people could view your vids thebiggerthebetter so they can realize how large some of the giant's in your huge tanks will get and are not for the average home aquarium.

 

[moe214]

I see two blacks. Rest look like red bellies. I don't know much of the yellow bellies as back when they were being brought in a little frequently the sales point were that they'd stay under 18"-20" I believe and they didn't so it was just that; a marketing thing. I will say if there is such I couldn't count with all the greedy cats lol but I definitely seen a pacu that was more silvery with a lighter belly and black tips on the fins which may be a "yellow belly".

 

[Boomer1224]

Beautiful Pacus a fish I always loved but could never own

 

[thebiggerthebetter]

Video update on 8 pacu in 4500 gal with feeding:

 

[pacu mom]

First video: 4:40, 6:51, 9:28 black pacu Colosomma macropomum
Their heads are more elongated, and the body shape is oval.

Red bellies have a more rhomboid shape. Red bellies have a more rounded head. They also have smaller adipose fins that lack rays. The adipose fin 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 the pacu has an adipose fin that he can move around like his dorsal fin, it is probably 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

Here are some 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/
http://www.seriouslyfish.com/species/colossoma-macropomum/

and our own JohnPTCs:

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 now 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.

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/amazon-gamefish-science/guide/tambaqui-pirapitinga.html

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.

Albino pacus are also Piaractus brachypomum, so are albino red bellies. I suspect the silver ones are just crosses of albino and regular run of the mill red belly. I seriously doubt that they are breeding a new type of pacu. The silver ones have the same morphology (rhomboidal shape) as all Piaractus brachypomum.

 

[pacu mom]

Second video: Black pacu at 1:29-1:42, 4:09

 

[moe214]

First video: 4:40, 6:51, 9:28 black pacu Colosomma macropomum
Their heads are more elongated, and the body shape is oval.

Red bellies have a more rhomboid shape. Red bellies have a more rounded head. They also have smaller adipose fins that lack rays. The adipose fin 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 the pacu has an adipose fin that he can move around like his dorsal fin, it is probably 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

Here are some 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/
http://www.seriouslyfish.com/species/colossoma-macropomum/

and our own JohnPTCs:

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 now 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.

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/amazon-gamefish-science/guide/tambaqui-pirapitinga.html

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.

Albino pacus are also Piaractus brachypomum, so are albino red bellies. I suspect the silver ones are just crosses of albino and regular run of the mill red belly. I seriously doubt that they are breeding a new type of pacu. The silver ones have the same morphology (rhomboidal shape) as all Piaractus brachypomum.

Much more detailed version of what I've been saying. One thing I see interesting is the weight being more for the black but them being more elongated. I read something awhile back I believe saying there's hybrids. That's what I always thought as the commons ones. Any light to shed if that's true or if it's just red bellies?

 

[pacu mom]

Much more detailed version of what I've been saying. One thing I see interesting is the weight being more for the black but them being more elongated. I read something awhile back I believe saying there's hybrids. That's what I always thought as the commons ones. Any light to shed if that's true or if it's just red bellies?

I also read the "hybrid" thing somewhere. There are other pacu breeds out there, but as far as I know, the big ones that need rescuing are mostly Piaractus brachypomum and Colossoma macropomum. I don't think the other pacu types get as big.

I joined a newly formed pacu forum, and recently did a search on pacu identification. Because red bellies lose their red color and assume a dark color very similar to black pacu, many people think they have blacks. I, too, thought I had blacks because they were dark and had no red. Blacks definitely look a lot different than red bellies. Their overall morphology is totally different from red bellies. The rayed adipose fins should clinch it when identifying them. I've also never seen pics of red bellies with the olive color that the OP mentions.

The other thing I've been searching out is gender determination. Males are more colorful. Males have longer dorsal fins--how do I compare that to anything? One article I read stated that males have a somewhat concave anal fin, while females have a somewhat convex anal fin. Huh? Females are broader when viewed from above. Another author who wrote an article on breeding pacu states that males have more pointed anal fins. I have messaged her and hope she responds back. Based on the somewhat concave/convex, I was horrified to discover convex anal fins on my pacu. So my boys are actually female. I cannot call them LeAnn and Donna after calling them Leonardo and Adonis for nearly 13 years. I am glad for this era of fluid gender identity--my fish can be whatever gender I identify them to be. I've been looking at pacu pics. The ones with the S-shaped anal fins are generally more streamlined looking and have brighter reds than the ones with fan-shaped anal fins who look more massive. I can also see that an S-shaped fin would look more pointed than a fan-shaped fin.