# Sexing rhoms



## below (Mar 26, 2004)

Is it true that the male rhombeus has a "hockey stick" shaped anal fin while the female's is straight, or is this all nonsense?


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## LaZy (Jun 17, 2003)

to hard your not gonna knoe until they bred


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## shutter13 (Jun 23, 2004)

you can either...

1) wait til they breed
2) cut it open and look for an egg sac

or

3) put in a piranha mating video and look for a boner


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## Judazzz (Jan 13, 2003)

shutter13 said:


> 3) put in a piranha mating video and look for a boner


 That's the method preferred by science
















Anyways, except wimple piranha's (and maybe an exception or two), piranha males and females look similar on the outside (ie. not sexually dimorphic) - I think rhoms belong to the latter group.
Rhoms however are extremely diverse in appearance and inhabit a very large range in the wild, so I'm not 100% sure (presonally, I do think so, but that's just gut feeling...)

*_Moved to Piranha Breeding_*


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## below (Mar 26, 2004)

I didn't think it was right, I just read it somehwere and wanted a second opinion. Thanks guys


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## pinchy (Jun 3, 2004)

Ive herd that too.


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## hastatus (Jan 16, 2003)

> below Posted on Aug 14 2004, 08:26 PM
> Is it true that the male rhombeus has a "hockey stick" shaped anal fin while the female's is straight, or is this all nonsense?


Nonsense. First anal fin rays are individualistic trait. Nothing to do with sexual dimorphism. Thickness can result from repeated bites (1 of many reasons) from other fishes and the end result is a thicker first anal fin ray.


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## mashunter18 (Jan 2, 2004)

> Anyways, except wimple piranha's (and maybe an exception or two), piranha males and females look similar on the outside (ie. not sexually dimorphic) - I think rhoms belong to the latter group.
> Rhoms however are extremely diverse in appearance and inhabit a very large range in the wild, so I'm not 100% sure (presonally, I do think so, but that's just gut feeling...)


yes pygopristus(dentics), are able to be sexed by the anal fin.

I believe I have 2 females and 1 male


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## hastatus (Jan 16, 2003)

Pygopristis denticulata have what is called a lobilae (lobe) seen in small juveniles (down to 1 1/2 in. TL) on the anal fin. So certainly one of the easiest to sex if you have good eyes on the young ones.







Older adults are easier to distinguish. Perhaps Pristobrycon maculipinnis might be another one with this feature. Remains unknown and unexamined except by me to see if this is the actual case. Catoprion mento, as mentioned above also has this feature (for your reference, I'm the discoverer of this feature (Magallanes, 1987).


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## MR.FREEZ (Jan 26, 2004)

> Catoprion mento, as mentioned above also has this feature (for your reference, I'm the discoverer of this feature (Magallanes, 1987).


i here someone tootin a horn







J/K man i really admire all the work you have done with

piranhas and your dedication


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## hastatus (Jan 16, 2003)

Sometimes its good to remind myself (and others) of things I do than just ID fish.


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## piranhaha (Mar 22, 2004)

where not worthy







!


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