sexing CA dither fish

Discussion about cichlids from Central America
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ayeo77
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sexing CA dither fish

Post by ayeo77 » Tue Apr 15, 2014 5:20 am

Has anyone got any info on sexing Astyanax Aenues and Brachyrhaphis holdridgei? Plus any requirements as they live with CA cichlids from Nicaragua?

thanks
Andrew

Bas Pels
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Re: sexing CA dither fish

Post by Bas Pels » Tue Apr 15, 2014 6:26 am

Brachyrapsis is a lifebearer - so these are sexable by looking at the gonopodium
Astyanax are sexable just as tetras are - females tend to be 'more filled' than males, less colored and often somewhat bigger

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Darrell Ullisch
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Re: sexing CA dither fish

Post by Darrell Ullisch » Tue Apr 15, 2014 9:40 am

As noted, the Brachyrhaphis are livebearers, and males have a gonopodium.

The Astyanax aeneus are very much like other large Tetras. I have a group of 12 thriving in a 125. The females are visibly deeper bodied, and when observed from the rear it is easy to see the sides bulging with eggs. Since moving to the 125, I've also noticed them getting longer than the males. Males are more slender, and tend to have a lot more red in the anal and caudal fins. They do best in large tanks due to their size and high level of activity; sexing wasn't easy until I moved them to the 125. I also feed twice a day rather than my usual once a day, and I'm sure this has helped in conditioning.
There are two kinds of error: blind credulity and piecemeal criticism. Sound skepticism is the necessary condition for good discernment; but piecemeal criticism is an error. - Egyptian proverb

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michi tobler
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Re: sexing CA dither fish

Post by michi tobler » Tue Apr 15, 2014 5:14 pm

Hi Andrew,
as already mentioned, Brachyrhaphis are easy to sex visually; the males will have a gonopodium and the females a regular anal fin. I disagree though that Astyanax can be sexed by body shape (got some data on that somewhere...). But there is an easy trick: males have microscopic hooks on the anal fin. When you grab the anal fin of a fish with two fingers and slide away from the body, males will have rough fins and females will have smooth fins.
Cheers, m
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Darrell Ullisch
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Re: sexing CA dither fish

Post by Darrell Ullisch » Wed Apr 16, 2014 9:30 am

I believe that the body depth difference only shows in older, more mature fish. I have a group of 12, 4 females (obvious due to being full of eggs) and the rest male. They are 3.5 inches plus, and the difference in body depth is quite visible. In younger fish it is very likely that this characteristic isn't as apparent.

I use a fine mesh net to check for anal hooks. Males will hang up in the net by their anal fin. Never tried sliding my fingers on the fin; not sure my fingers are that sensitive after 30+ years of machining callouses! :)
There are two kinds of error: blind credulity and piecemeal criticism. Sound skepticism is the necessary condition for good discernment; but piecemeal criticism is an error. - Egyptian proverb

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