Sexing synspillum

tiger15

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Oct 1, 2012
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I've never heard of using eye color to sex fish until I read Lee's article. He said that sexually active male syns all have blue color, and females yellow, so apparently it only applies to mature specimens. On closer look of my Viejas collection, my male Syns, male Melanurum and a blue male Fenestratus all have blue eyes. The only male Vieja that has yellow eyes is my pink/white Fenestratus which may have to do with its lacking of pigmentation. I have two immature V. bifas, one has blue eyes and the other yellow. Time will tell if their eye color will determine their sex.
 

Rocksor

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Nov 28, 2011
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I've never heard of using eye color to sex fish until I read Lee's article. He said that sexually active male syns all have blue color, and females yellow, so apparently it only applies to mature specimens. On closer look of my Viejas collection, my male Syns, male Melanurum and a blue male Fenestratus all have blue eyes. The only male Vieja that has yellow eyes is my pink/white Fenestratus which may have to do with its lacking of pigmentation. I have two immature V. bifas, one has blue eyes and the other yellow. Time will tell if their eye color will determine their sex.
Here's a confirmed sexually mature female bifa on the left and sexually mature male bifa on the right. The male still has a bit of yellow in the eye.

 

nutty

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Jan 4, 2007
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Hi Guys,

Thanks for taking interest in my article.

Just a couple of points to clear up. The article only discusses both melanura/synspila populations and not any other fishes assigned to the same group, so I can't say for sure if they display similar sexual traits regarding eye colour. We can always sex fish by morphology observations, such as flowing unpaired fins, cranial profiles, colour, venting etc....

The eye colour is only displayed when both fish are showing dominance or sexually active (pre-spawning behaviour). This doesn't mean sexually mature. I doubt you will notice this eye colour by just keeping single sexually mature specimens?

Just a couple of photo examples to give a better idea of my point, both photos show pre-spawning fish.

Vieja melanura (synspila) pink headed morph



Vieja melanura, orange morph, male and two females.



Cheers,

Lee.
 
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tiger15

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Just to clarify that I keep an all male tank of mature 10 to 14" melanurus (lake Peten), synspillum, blue and pink fenestratus. All except the pink fenestratus have blue eye despite not being sexually active.
 
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