Our 7+1 pacu

[thebiggerthebetter]

Thank you guys, especially pacu mom - wonderful write-up and links that taught me the essentials of pacu ID in minutes. Greatly appreciated. This explains a lot.

So it's all about red and black, right? Are the yellow bellies off the table? Moe and Alex mentioned the yellows.

You have preemptively answered the question posed in my next pacu video haha, which is about a pair of a black pacu Toyin of Rehoboth Aquatics sent me 2.5 years ago.

BTW, the literature says black get bigger than red. Yet, my blacks are still smaller. Perhaps they just grow slower and eventually will overtake the reds. But right now, despite similar age, they are 1/2 the size by weight of all my reds.

 

[pacu mom]

Please do me a favor and compare the adipose fins of the blacks and red bellies. The blacks adipose fins have rays, the red bellies do not. (from the articles I have read) Can you confirm that for me? I can say that the adipose fins on my pacu look just like a skin extension and just flop around. Since you have both, you can do all the comparisons. Blacks look so different to me, since I've never seen one in person.

 

[moe214]

I always ID'd large ones easily. I read in 5th or 6th that blacks were slimmer and more elongated and that their upper body was lighter than the lower half. I searched YouTube of aquariums etc and found videos, it's a clear difference. I always felt a little disregarded when I ID'd a black on here lol but whatever I can tell them and they can do what they want with it both get big. As far as the gender ID can't say I've only kept two. When they first started becoming available I was in elemtary school and got it with some SD thinking it was another species of SD but I did see a clear difference. Got another one when I was 14 and had a bigger tank. Grew it out and ended up bringing it to my lfs, decided I'd never keep another fish I couldn't house cause of them lol. Can't say I haven't made mistakes since but they've been far and few in between.

 

[moe214]

And as far as the yellow bellies. Can't say I've done any deep digging just skimmed the surface. Neither of yours are it if you asked me.

 

[pacu mom]

My observation is that some people post videos of their fish on YouTube, and all of a sudden they consider themselves "experts". There is so much misinformation on the web, that a person doing their best to research "facts" will probably get some misinformation.

I have never read about "yellow pacu". Perhaps MFK has some "experts" too. There are other fish called "pacu". The literature can be outdated and/or erroneous. Even Wikipedia has erroneous information. Apparently, anyone can contribute to Wikipedia. Just this morning, I did a search on "types of pacu". Wikipedia has the picture of a black pacu for "pacu" where the picture is correctly labeled Colossoma macroponum, and then the same black pacu picture is shown for Piaractus and for Piaractus brachyponum.

This article lists various types of pacu, but the list has old nomenclature for some of the fish. The statement that pacu are more sensitive to nitrogen waste products than other fish from their region is a good statement that I have never read any where else.
http://www.fishdeals.com/characins/pacu/
I belonged to a pacu forum that went defunct 6 months after I joined when both moderators suddenly lost their 2 year old pacu kept in 75 gallon tanks. Fish that have the potential to live 30+ years shouldn't be suddenly dying at 2 years old. I've seen my pacu gasping when their tank was uncycled. Their gasping only stopped when I changed out enough water to remove the ammonia and nitrites. I am convinced that good water parameters are a must to keep these big guys alive. I am no expert, but I have managed to keep my pacu alive for nearly 13 years.

As I've been writing this, I have also been in contact with Wikipedia. The erroneous black pacu pictures have been removed from the Piaractus and Piaractus brachypomus sites! YES!!!

 

[moe214]

I believe jeff began bringing the yellows in. They indeed do have a yellow sheen on their body or maybe golden. They weren't talked about a lot for awhile because they were said to top out at 18" but I doubt that highly one guy reported his growing to 12" at a fast rate maybe larger don't remember clearly.

They honestly look like red bellies shape wise but just a yellow golden color on their lower body

 

[pacu mom]

OK, I found it--Piaractus mesopotamicus, the small scaled pacu. Max length around16", max wt 44 pounds.

 

[moe214]

OK, I found it--Piaractus mesopotamicus, the small scaled pacu. Max length around16", max wt 44 pounds.

Doesn't add up see lol. I suspect they may grow smaller than black and red but still quite large regardless. It is tall bodied like the red belly

 

[thebiggerthebetter]

Thank you much for all these, PacuMom and Moe. I am learning.

Moe, I'd think that a rather subdued variation in the color of the belly while keeping all the looks and body structure of a red belly could mean that this common name has not a real species behind it. It also could simply stem from a difference in diet, for instance an inclusion of carrot with its load of yellow, orange, and red pigments. Or an age thing - a red belly pacu in transition from the red-bellied and red breasted juvenile coloration to the grey / silver subadult / adult.

Jeff Rapps has labelled fish wrong before, especially non-cichlds. And that's ok.

Moe, can you find a serious article / write-up / reference, scientific or popular scientific, mentioning the existence of the yellow belly and matching it with a taxonomic name?

PacuMom, I will observe closely the adipose fins on my pacu and will report back.

 

[pacu mom]

Here are several sites discussing Piaractus mesopotamicus:

https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=428


This article says they can get 2' (I realize Wikipedia is a scholarly site)
https://en.wikipedia.org/wiki/Piaractus_mesopotamicus

http://www.fishbase.org/summary/55383


Here's a fishing site with pictures of Piaractus mesopotamicus
http://bigfishesoftheworld.blogspot.com/2012/04/pacu-piaractus-mesopotamicus.html