# RHOM?



## PARANHAZ69 (Dec 16, 2003)

I've had this guy for a little over a year and a half. he's about 2 years old now. almost 4". is he a rhom? he's pretty active and aggressive. here are some pix from beginning to now. thanks guys.


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## hastatus (Jan 16, 2003)

Fairly certain it is S. rhombeus.


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## PARANHAZ69 (Dec 16, 2003)

thank you frank


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## rchan11 (May 6, 2004)

He's growing nicely.


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## mr.shawn (Oct 28, 2004)

what size tank do you have because you said that he is about 2 years....... right........ is
the picture you show is now or a year ago because 2 year piranha would be a hand size or bigger............... just wondering???????????????


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## Death in #'s (Apr 29, 2003)

what have u been feeding him
he should be alot bigger than that


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## compton ass steve (Nov 12, 2004)

hmm...never seen a rhom with red fins


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## PARANHAZ69 (Dec 16, 2003)

he is in a 30gal and he always has guppies in his tank and he eats small goldfish and pellets. he is fed daily and he eats infront of me so i know he eats well. i feed all of my fish daily. i have to clean more often but i think its worth it. he was sold as a rhom by an lfs, but i will have to wait till he gets bigger. thanks all


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## hastatus (Jan 16, 2003)

The problem with juveniles rhombeus-group fishes, occasionally Pristobrycon can fool even experts in thinking what they are looking as S. rhombeus, which is my hesitation on being 'fairly' certain. The extra photos you've posted make me hesitate because a couple of them look "pristobrycon-like". The bars, spots and head shape put it in that area.

Allow it more time to grow out and keep a good catologue on its growth. I'd like to revisit your fish again when its grown more.


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## PARANHAZ69 (Dec 16, 2003)

will do frank


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## Judazzz (Jan 13, 2003)

Looks like that fish has a "Manueli-style" caudal fin - no dark terminal band and a prominent V at the base.
I thought Rhoms had more Nattereri-like tails, dark terminal band and base, without the distinct V-shape (I know, the comparisons are hardly scientific, if at all, but it's the easiest way to compare, imo.)
Could it be because of the size of the fish - 4" for a 2-year old Rhom doesn't seem much to me...

Or am I just way off?


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## hastatus (Jan 16, 2003)

> Judazzz Posted Today, 12:14 PM
> Looks like that fish has a "Manueli-style" caudal fin - no dark terminal band and a prominent V at the base.
> I thought Rhoms had more Nattereri-like tails, dark terminal band and base, without the distinct V-shape (I know, the comparisons are hardly scientific, if at all, but it's the easiest way to compare, imo.)
> Could it be because of the size of the fish - 4" for a 2-year old Rhom doesn't seem much to me...
> ...


I'll answer it this way, some subadult Serrasalmus rhombeus have a dark "V" at the caudal and a faint band at the tail until past subadult. The compressus group, in particular S. altuvei can have a dark "V" at small sizes later grow out and have a dark band just like S. rhombeus. Pristobrycon can have both a dark "V" and a terminal band depending where they are in age. Its very interchangeable. That's why some compressus group fishes are mistaken for S. marginatus which predominately has a dark "V" throughout its life until maturity when the tail darkens nearly completely to just a hyaline edge (like S. maculatus). ON his photos, I'm thrown by the added photos of what appears to be a Pristobrycon.


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## Judazzz (Jan 13, 2003)

Aaah, I see...
Thanks for clearing that up, Frank


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## hastatus (Jan 16, 2003)

> Judazzz Posted Today, 12:45 PM
> Aaah, I see...
> Thanks for clearing that up, Frank


One last thing, Antonio Machado when he revised the genus/species of S. eigenmanni made a remark that this species confused him because of the ontogeny, meaning the strong resemblence to a Serrasalmus species (rhomboid body, pointy snout) to later developing into a Pristobrycon appearance (small snout, laterally compress body).


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## PiranhaMaster (Oct 21, 2003)

hastatus said:


> One last thing, Antonio Machado when he revised the genus/species of S. eigenmanni made a remark that this species confused him because of the ontogeny, meaning the strong resemblence to a Serrasalmus species (rhomboid body, pointy snout) to later developing into a Pristobrycon appearance (small snout, laterally compress body).
> [snapback]851096[/snapback]​


oh, now you come around









http://www.piranha-fury.com/pfury/index.ph...topic=29027&hl=

From last year


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## hastatus (Jan 16, 2003)

Come around to what?



> PiranhaMaster Feb 9 2004, 10:14 AM
> 
> ok, first it is way too small for an ID but that being said it does not appear to be S.Rhombeus at this time. There are many varients of S.Rhombeus so only time will tell. By just looking at this very small specimen with rounded snout and very large eye I am going to GUESS that it is in the Pristobrycon Genus. Possible eigenmanni. Again at this stage in it's development there is no way to be certain and may infact look completely different with another inch or two added.
> 
> ...


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## jamesdelanoche (Dec 15, 2004)

is the fact he could hold it in his hand any evidence? I've never heard of a rhom being that docile but i'm just throwing ideas out there


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## marky (Sep 4, 2004)

Wow he small for 2 years but cute!


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## hastatus (Jan 16, 2003)

The big problem (that I have) in PID is to much usage of variable photos. If the hobbyist would just select 2 good (clear) photos w/o angle that would help so much more. In the case of the above photos, the chronological order is off and hard to tell in what order of growth (and age) they appear. Certainly looks like 2 different species being shown which clouds the issue more. I don't disagree much of PiranhaMaster regarding placement of the fish as a Pristobrycon. The issue is not being right on the "guess" as much as being able to get a good image to resolve the ID issue. My impression at the young ages was S. rhombeus in the original thread. Subsequent photos (if it is the same fish) begin to show tell-tale signs of bars and spots, consistent with compressus-group member. Yet the snout as it begins to develop more (and body) begins to laterally compress suggesting a Pristobrycon. Is it S. eigenmanni? Don't know without having the actual collection point as many of these humeralis-type fish are extremely close in appearance. So even if we can agree the fish in question is a Pristobrycon, it still leaves the question which species. And only time will reveal that based on how well the photos are taken and displayed.


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## Death in #'s (Apr 29, 2003)

compton ass steve said:


> hmm...never seen a rhom with red fins
> [snapback]850139[/snapback]​


alot of juvi rhoms have red fins


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