Apisto sex ratio effected by?

[ihavefishwantmore]

Does water hardness,PH, or temp; effect the ratio of males to females in apisto's?

 

[depthc]

I believe it depends on the temperature being very stable during the first few weeks of hatching. In Romers book it says that 26 degrees C is the temperature that produces roughly equal numbers of male and females. If it drops above or below the temperature or temperature range, sex ratios change in both directions either producing a majority of males or females.

Can anyone else correct me or add some more? Im not that educated in this aspect yet.

Andrew

 

[_BaDgUy_]

I've read that section in the Cichlid Atlas, and done my own experiments, which gave the same results as the book.

26C seems to be the "even" point for the sexes.

Higher will give more males.

Lower will give more females.

The more the temperature varies from the 26C point, the more the sexes get more defined, for example, many mores males than females if the temp is at 30C.

But, not all species are the same. Some might not be affected by this "rule".
The ones I've worked with up to today have followed the rule pretty well. I'm still keeping a record as new spawns show up!!

I have not had the chance to work with the pH to have different ratios yet.

 

[ihavefishwantmore]

Thanks. David when you tested this did you only maintain the temp for the first few weeks? If I am trying to achive a higher number of males, can I bring the temp back down to finish raising them?

 

[Peter Lovett1]

Though temperature does play a very large role in the sex determination of Apistogramma fry it is no way as simple as just getting the temp. At 26c you can still get 100% female and 100% male broods but over many spawns you will reach a 50:50 ratio. As the temperature rise or gos down the Max % of each reduces and will then give either more females or more males.

Most of me experience has come form Apistogramma sp. “Inca†will over 15 spawns with wide venations in the sex ratio at 26c but I would say that at the end of the day I have ended up with about 50:50 at 26.

 

[_BaDgUy_]

Thanks. David when you tested this did you only maintain the temp for the first few weeks? If I am trying to achive a higher number of males, can I bring the temp back down to finish raising them?

Hi,

Sorry for the delay... been kind of busy the last few days!!

All the tests I did, or mostly my observations, were all done with a constant temperature.

With the readings I did in the Cichlid Atlas on the subject, it is said that it is possible to change the temp after a certain time, without modifying the sex ratio.

You should get the Cichlid Atlas by Uwe Römer.. very good reading on that particular subject!!