CichlidFish.com - Fish That Think.

Interested in any information on the max adult size of Metynnis maculatus, which is the fish that many pet departments are selling as the red-bellied Pacu. Most "academic" sites (including Fishbase and it's mirrors) list max size as 18cm (which is a tad over 7 inches) but we've heard from other sources that this creature can attain 48" under proper conditions. Anybody have any insights or experience with this sp?

--Mark:cool:

hmm 18 to 20 centimeters. (that's what I've read too but 48" sounds like a different type doubt there could be so much variation in growth! )

If you actually find Metynnis maculatus (labeled correctly) in a store they will on get to an average of 5-8"

which is the fish that many pet departments are selling as the red-bellied Pacu

Most of the pacu's sold as red bellied pacus in my area are one of the Colossoma species that get 20"-40"+

Metynnis maculatus in my area are sold as red bellied silver dollars but 80% of the time they're not M.maculatus but a different species of Metynnis.

I found another source, a manual published by Axelrod in 1955 that sez max size 8". Thanks guys for the info --

--Mark:cool:

pacus and Os, thin theyll go together?? (smaller pacus obviously) ive heard silver dollars will go with an O, and my tank is looking pretty dull with my baby just waiting for food.

Originally posted by Craig
pacus and Os, thin theyll go together?? (smaller pacus obviously)

Yes -- they're classic tankmates, but should only be put together in large aquaria (150g min I would think). They're actually quite comical together. I have a tank with a pair of Oscars (Ricky and Lucy) and a Red Bellied Pacu (Pacu Pete). Pete out-eats the Oscars any day of the week (as Pacus do ). As you know, when Oscars eat, a lot of shredded food comes out the gills, and Pete likes to hang around under the Oscars to munch the discarded food. When it's not feeding time, though, he still keeps posting himself under the Oscars, venturing up from time to time to "nip" at their bellies, waiting for some food to come out - it's hilarious. Ricky and Lucy get irritated and nip back sometimes, sending Pete on a mad panic-driven dash across the aquarium. They're quite a team, them three

--Mark:cool:

right,.... 150 gal... dont have that, lol

silvar dollars are a similar species right? me thinks ill get a shoal of them

actualy, pacus and silver dollars both have similar body shapes and jaw build and both love veg matter, are they the same genus?

actualy, pacus and silver dollars both have similar body shapes and jaw build and both love veg matter, are they the same genus?

No


most true Pacus = Colossoma
most true Silver dollars = Metynnis, Mylossoma


The other 6-7 genus's fit in where ever someone decides they belong on a given day

Originally posted by stilllearnin
No


most true Pacus = Colossoma
most true Silver dollars = Metynnis, Mylossoma


The other 6-7 genus's fit in where ever someone decides they belong on a given day

True. When it comes to Pacus, I've rarely seen as much confusion and disagreement in regards common and scientific names. I've heard both ways, that Pacus and Silver Dollars are closely related or not; and who's to say which authority is correct? Some sites I've visited claim there's only 2 Pacu species (both Colossoma, and both h*u*g*e); but Fishbase sez there's 10 or more, and most of them small. The term "Red Bellied Pacu" has been applied to at least 3 scientific names that I know of; I don't have them in front of me, but they're Colossoma, Myleus (sp?), and Metynnis. AAArrrggghhhh!!!!!

--Mark:cool:

I have a friend that had a pacu that he threw into his 75Gal tank, with the following occupants:
2 Oscars
1 Wild Gar
2 Snapping Turtles
2 Breeding Blue African Cichlids
3 Other types of Cichlids
and the Pacu


And while the pacu NEVER Touched the Oscars (Oscars being the most dominant in the tank), It did however kill both Turtles, Every Cichlid except one of the Blue African's, and made an attempt to kill the Wild Gar....which was a fight that was fought in vain--the Gar killed the pacu with little effort. The death of one of his Blue African Cichlids mad my friend very unhappy, if the Gar hadn't of killed the pacu, I'm sure he would of.

I've heard both ways, that Pacus and Silver Dollars are closely related or not; and who's to say which authority is correct?

The last classification done (that I read ) Pygocentrus, (True Piranhas) Serrasalmus,(Piranhas/pirambebas) Pristobrycon,(pirambebas) Pygopristis (pirambebas), Catoprion (Wimple Piranha), Mylossoma (silver dollars) and Metynnis (silver dollars). Were all considered a closely related family (pretty much piranhas) but with valid seperated genus's.


Pacus/tambaqui (all species), other species of silver dollars, etc
were considered another family.

Seems they split the silver dollars up by teeth type and wild dietary habits


at least until someone changes their mind again :hahaha:

Fishbase is one of the best sites around :thumbsup:
but it seems to be fairly outdated in sections.

The best site I know of for current info on Silver Dollars,Pacus and Piranhas is http://www.opefe.com

Originally posted by stilllearnin


The best site I know of for current info on Silver Dollars,Pacus and Piranhas is http://www.opefe.com

Thanks, I'll take a look at the site --

--Mark:cool:

Are these sometimes labelled as "spotted silver dollars"? A LFS near me has in a tank labelled Red Belly Pacu/ spotted silver dollars. I guess there just as confused and putting two names

Originally posted by stilllearnin


The best site I know of for current info on Silver Dollars,Pacus and Piranhas is http://www.opefe.com

Thanks for this link -- just did some research at this site, and it is evident that the "Metynnis" species that I started this discussion about is actually "Piaractus brachypomum", which is a Pacu that grows to around 24" adult size. The distinguishing feature for this species is the blotch on each gill cover, mentioned at the website and present on all the little fishes for sale as "Red Bellied Pacu" down at the local Petsmart. Petsmart claims an adult size for this fish as 22", which is close, but Wal Mart is selling the same critter to unsuspecting ten-gallon tank owners claiming a max size of 10". Reading the artical at http://www.opefe.com makes me believe this fish is not appropriate for aquariums, especially those owned by Wal Mart browsers - - -

Link to the site: http://www.opefe.com/piaractus.html

--Mark:cool:

Another great site I just ran across re: pirhanas, pacu and silver dollars:

http://www.wetwebmedia.com/FWSubWebIndex/serrasalminae1.htm

--Mark:cool: