Talk:Piaractus brachypomus

photo request

Is this correct fish?

Tambaqui fish (colossoma bidens)

--Traveler100 (talk) 13:08, 10 April 2010 (UTC)

I'm not sure. The image says it is, but Russian Wikipedia uses that image for Colossoma macropomum. Of course they may be the ones getting it wrong. French wikipedia uses it on the Piaractus brachypomus article though their general Pacu article says its Colossoma macropomum same as the Russian Wiki. See also the new discussion about a different image, hopefully a way to ID these fish comes out of that. --HighFlyingFish (talk) 18:51, 16 February 2018 (UTC)

Care information

Someone removed information from the page, because it talked about caring for this fish, however a lot of aquariume fish articles contain care information. If no one objects I will restore the info.--HighFlyingFish (talk) 18:38, 21 March 2010 (UTC)

Removal of Image

@Vermont: removed the image File:Colossoma-brachypomus.jpg from this article saying it was the wrong fish. Why do you say that? I see nothing on commons indicating that's not the right fish. Also going to ping @Stevenj: as he is the author of the image. --HighFlyingFish (talk) 18:40, 16 February 2018 (UTC)

I reverted the deletion, as no rationale was provided to suggest this was the wrong fish. If your going to remove the image please explain why this isn't the right fish. --HighFlyingFish (talk) 23:03, 20 February 2018 (UTC)

Also opened a discussion at File talk:Colossoma-brachypomus.jpg to get consensus on the subject. --HighFlyingFish (talk) 22:25, 21 February 2018 (UTC)

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Here is a discussion between me and @Vermont: that explains some of the rationale behind the deletion of the image:

Please reply on the talk page regarding the rationale for the File:Colossoma-brachypomus.jpg you removed being a depiction of the wrong fish. I see nothing on Commons indicating its not Piaractus brachypomus. --HighFlyingFish (talk) 18:43, 16 February 2018 (UTC)

I reverted the deletion, as no rationale was provided to suggest this was the wrong fish. If your going to remove the image please explain why this isn't the right fish. --HighFlyingFish (talk) 23:04, 20 February 2018 (UTC)

@HighFlyingFish: I was sure I replied to this earlier, it seems I didn't. I was informed on IRC in the #wikipedia-en-help channel by someone complaining about the incorrect fish being shown there. They could not figure out how to edit, so I did a little bit of checking and saw that the image was titled "Colossoma-brachypomus", and in the article "Piaractus brachypomus". Piaractus brachypomus being a red-bellied Pacu. On the Pacu article, it was referred to as a "Black Pacu". This looked to me to be enough to conclude that it was, in fact, not a red-bellied pacu. Nice username by the way, and happy editing! _{Vermont | reply here} 23:42, 20 February 2018 (UTC)

Huh, that's strange. There's no fish called "Colossoma brachypomus". The genus Colossoma has only one species, Colossoma macropomum, the Tambaqui. "Colossoma brachypomus" is an outdated synonym for Piaractus brachypomus which is why the image's title supported this being the right fish to me. But you're right that other articles on this wiki, and other articles on other wikis disagree. --HighFlyingFish (talk) 20:54, 21 February 2018 (UTC)

Also, is it alright for me to copy this discussion onto the article's talk page where other editors can see it? In general it would be good to have it in a more visible place. I'm also going to bring the issue up on the File's talk page and on commons to try to get a consensus. --HighFlyingFish (talk) 22:20, 21 February 2018 (UTC)

Good idea. _{Vermont | reply here} 22:21, 21 February 2018 (UTC)

Alright will do. I also opened a discussion at File talk:Colossoma-brachypomus.jpg. --HighFlyingFish (talk) 22:26, 21 February 2018 (UTC)

I agree that it looks more like a black pacu, which is of course not red-bellied, but still belonging to Piaractus brachypomus, formerly known as Colossoma brachypomum (Cuvier, 1818)? It seems one way to distinguish those two species is that the name brachypomus comes from rom brachy (= short), and pomum (= operculum), referring to shorter operculum compared to Colossoma macropomum. (Source: Wikispecies) Dan Koehl (talk) 22:50, 24 February 2018 (UTC)

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--HighFlyingFish (talk) 22:27, 21 February 2018 (UTC)

I'm quite certain the lead image on Tambaqui is actually the red-bellied pacu, but I'm not quite sure about the image in question here… Color is not the most reliable way to identify fish species because it can vary genetically but can also be manipulated in many species. P. brachypomus definitely loses its red coloration as it matures so the name "red-bellied pacu" means basically nothing, and the top image could be a good candidate. I did start with color though and this site, though not the most inherently reliable, points out that P. brachypomus is typically light blue-gray/steely gray dorsally and darker gray/brownish gray ventrally while Colossoma macropomum is golden/olive green dorsally and purple/black ventrally.

The golden/olive green ended up making it easy to quickly see the difference using FishBase images. This one is of P. brachypomus (from here) and this one is of C. macropomum (from here). The coloration is clearly different, and this source used in the article points out a few morphological differences between the two species, of which we can see the operculum and adipose fin; the operculum is shaped like a half moon in C. macropomum and smaller in P. brachypomus, and the adipose fin is a little more significant in C. macropomum and has rays that are lacking in P. brachypomus.

So File:Schwarzer Pacu Colossoma macropomum Tierpark Hellabrunn-1.jpg at Tambaqui has all of the (available) characteristics of P. brachypomus. With the image in question here, the coloration is iffy, the operculum seems to definitely indicate C. macropomum, and the adipose fin seems to indicate P. brachypomus but isn't very visible. Coloration could easily be that of C. macropomum and I'd say the operculum is a more reliable indicator than the fin, so C. macropomum? All three fish in the image above in #photo request, File:TambaquiVeracrz.JPG, must be C. macropomum. Rhinopias (talk) 23:54, 24 February 2018 (UTC)

This is certainly a tough question. Based on [1], it's important to consider the height:width ratio of the opercle. And after staring for a long time at [2] and [3], there is indeed a difference. For P. brachypomus the operculum forms a sort of part-circle behind the eye, and is what USGS describes as "short": it does not extend very far towards the posterior. For C. macropomum, it's more crescent-shaped, and extends considerably farther away from the eye, posterior and ventral. So there is a smaller relative area between the eye and the operculum for P. brachypomus, and a larger area for C. macropomum. Once one notices it, it becomes fairly recognizable. On that basis, I think the juvenile image on this page is correctly identified as P. brachypomus, but the contested adult image is C. macropomum. It's a visible difference in area behind the eye. I think the image above, at #photo request, is also C. macropomum. At Tambaqui, the lower image is also C. macropomum, while the lead image probably is C. macropomum too, but it's harder to be sure. --Tryptofish (talk) 20:33, 25 February 2018 (UTC)

What it sounds like so far is that there's currently no consensus about File:Schwarzer Pacu Colossoma macropomum Tierpark Hellabrunn-1.jpg, though it might be this fish, but there is an emerging consensus that File:Colossoma-brachypomus.jpg is in fact C. macropomum. In light of this, I have reverted myself and restored the version without the contested image. --HighFlyingFish (talk) 22:20, 25 February 2018 (UTC)

I took the image at the New England Aquarium, and labeled it according to the label in the aquarium display; I have no expertise in fish identification myself. It is possible that the aquarium display was out of date, I suppose. — Steven G. Johnson (talk) 18:37, 16 May 2019 (UTC)