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Sexing piranhas

642 Views 8 Replies 7 Participants Last post by  The_Spoot
Is there a reliable way of sexing s.rhombeus, does anyone know? I have an idea that the anal fin shape is different between the sexes, but I don't know which shape is which sex.

Not the best of pics, but it gives an you the shape of my rhom's anal fin.

Rich
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as far as I have heard from frank (hastatus), there is no way to sex piranhas without dissecting them.
Thanks you Sir...guess I'll have to ask Frank.

Rich
caribekeeper Posted Today, 01:59 AM
Is there a reliable way of sexing s.rhombeus, does anyone know? I have an idea that the anal fin shape is different between the sexes, but I don't know which shape is which sex.

Not the best of pics, but it gives an you the shape of my rhom's anal fin.
This observation has been on-going since the 1950's. In particular, when it was first suggested by Baench. Its long since been discounted by science. With the exception of Pygopristis denticulata which has a bilobed anal fin, the shape is an individualistic trait. What that means is, S. rhombeus 1) like humans that have individual traits (long noses vs short noses, color shades, etc.,), so it is with the anal fin. 2) Add to this the fact they are fin biters and the anal fin being one of the areas frequently bitten, the regrowth will vary in size by the number of bites the fish receives. In other words, it doesn't always grow back the way it originally looked.

I still find remarks about thickness of first ray, length of anal fin, etc., being discussed by web sites and forums being an indicator for sex determination (sexual dimorphism). Unfortunately, it's an observation that is from the uninformed who think they've "discovered" something.

Thanks for asking.
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i dotn think you can tell
mori0174 said:
as far as I have heard from frank (hastatus), there is no way to sex piranhas without dissecting them.
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Thanks Frank and everyone who assisted there...I appreciate it.

Regards,
Rich
not possible in a home aquarium. frank knows though. try some barry white that might work
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