# Help with ID please



## KISS (Feb 2, 2007)

A friend got this fish from a LFS, not too sure what it is. Please help with ID.

Thanks,

KISS


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## SNAKEBITE (Oct 7, 2006)

S. Rhombeus


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## FohDatAss (Oct 7, 2003)

Rhom without a doubt...


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## KISS (Feb 2, 2007)

Thanks. Rhom is what I thought. However, someones said it could be an inbreed one. So just wondering if it is any possibles that S.Rhom could inbreed in wild.


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## 2PiRaNhA~2FuRrY (Nov 1, 2005)

I am thinking is Serrasalmus Irritans


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## Dawgz (Aug 18, 2005)

that fish is definitly not an irritans.


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## FohDatAss (Oct 7, 2003)

I feel like its maybe not a rhom the second time around, maybe not, anyway *its definatly not inbred*...rhoms come in many shapes and sizes...depends wherethe fish came from...All serras breed in the wild not captive, so the odds its inbred are slim to none IMO...Do you know where your serra came from?

Hastatus aka Frank will give you a positive ID


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## 77gp454 (Feb 18, 2007)

If that is a rhom it's the most elongated rhom I have ever seen.


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## SNAKEBITE (Oct 7, 2006)

77gp454 said:


> If that is a rhom it's the most elongated rhom I have ever seen.


you havent seen much rhoms have you...

like i stated above S. Rhombeus


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## FohDatAss (Oct 7, 2003)

could be gibbus although I think its a rhom...

its gotta be a rhom i check the gibbus picture on AquaScape...

not the same structure


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## Dr. Giggles (Oct 18, 2003)

Tail and eye tell me its a Rhom


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## cfb (Mar 14, 2007)

Rhombs come in all shapes and sizes which sometimes makes their ID more difficult. The Rio Araguaia river in Brazil produces Rhombs that have a more elongated body shape, similar to S. Gibbus.

Black band on the tail fin and red eye suggest Rhomb to me.

As far as interbreeding, read this from OPEFE

"The problem of rhombeus nomenclature and description is a big one. There are several forms widely distributed. The form living in the Guiana's are slender, while forms living in the Orinoco, Amazonas and other South American rivers are deeper and very dark. The only thing common is that they have a red eye. Scientists believe that S. rhombeus is a complex of species. Both Dr. W.L. Fink and Dr. Antonio Machado-Allison are still working with the Brazilian species. According to Nakayama et al (unpubl) fishes from Catalão Lake (a mixed water ecotone) which is formed by water from the Solimões River (white waters) and the ***** River (acid and dark waters), this environment caused some changes in chromomsomes in this species. *This melting together (or fusion) of the centromere (=the centromere consists of fibres and holds together two to create a chromosome) by the eggs released by these species may have been caused by interbreeding. In previous discussions with a field researcher (1995) I discussed this topic of Serrasalmus species (in particular S. spilopleura) interbreeding and new populations forming after being cutoff from main rivers. At that time he thought it was unlikely. This new DNA information is changing this perception.*" 3/26/2007 was the date of the last page update.

Randy
CFB


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## FohDatAss (Oct 7, 2003)

Dr. Giggles said:


> Tail and eye tell me its a Rhom


I could be wrong but I dont think you can make an accurate assumption on what groupmemeber the fish is in based on eye and tail alone...I thought it had to do with bone structure/skeletal makeup of the fish...

look at the two differences in tail with two different s.compressus group memebers tails...

more example of same group member...s.comp

I am not in anyway saying i'm right...I want Frank to come in here and explain


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## Piranha Guru (Nov 24, 2005)

mR. Blueberry said:


> Tail and eye tell me its a Rhom


I could be wrong but I dont think you can make an accurate assumption on what groupmemeber the fish is in based on eye and tail alone...I thought it had to do with bone structure/skeletal makeup of the fish...

[/quote]

An accurate assumption...yes, a positive ID not necessarily. The tail is actually an important ID factor...shape, presence/characteristics of terminal band, presence/characteristics of anterior band. Combine that with the eye and you can narrow species down quite considerably...red eye, yellow eye, clear eye, band through eye, etc...

The heavy terminal tail band and sqaured off end of the tail is quite common in the rhoms I've seen. Compared to compressus, other than the dinner plate sized one (that thing is a BEAST), the majority I've seen postiviely ID'd have a more V-shaped tail.

You have to make assumptions from what data you are provided. You will never get bone structure/skeletal makeup from a picture of a living specimen. You can, however, possibly get visible characteristics (tail shape/banding, eye, spots, etc..), scale counts, dorsal fin rays, serrae, and general body shape versus head shape. I believe this is the typical information Frank tries to glean from a good photo. Unfortunately you can't get it all, and that's why even Frank's ID's are best guess...although I'll take his worst guess over my best guess anyday.


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## Piranha Guru (Nov 24, 2005)

mR. Blueberry said:


> could be gibbus although I think its a rhom...
> 
> its gotta be a rhom i check the gibbus picture on AquaScape...
> 
> not the same structure


Be careful with using one picture to count or discount a species (not that I'm saying you're wrong).

There is a reason all good Field Guides use drawings and not pictures...a drawing can show ALL the visible charactersitics needed for a reliable ID that a photo can't.


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