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Does water temperature have any influence on what sex fry will become?

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  • Does water temperature have any influence on what sex fry will become?

    Just putting this out there.

    I was breeding Endlers at quite a high temperature, I think about 28 degrees. I would tend to get a higher percentage of male endlers than female.
    I had a mate breeding endlers at a lower temperature, about 24 degrees, he would tend to get more females than males.

    Was this just coincidence or does the temperature influence it at all.



  • #2
    I do not believe for one moment it is a coincidence.
    Chardy sippin', bitter, twisted, sour 'ol cow. Do not let your fantasies run away with your capabilities .... you, boy, are NO match for my blow torch! Boguns, you just keep on rollin'


    • #3
      Yep, apperently its supposed to be true but like everything people will argue it for and against!

      Funnily enough I've just started doing an experiment in two identical tanks with different temps (high and low) with endlers to see for myself. Purely because I was ONLY getting female endler fry at 24oC and desperatly want males!



      • #4
        It will make a difference as will the Ph.


        • #5
          Nice one Surfydave,

          You will have to let us know the the results.

          I didn't realise about the pH influencing it as well.


          • #6
            Absolutely correct about environmental conditions affecting sex of all poecilia. And I'm beginning to believe it also influences the sex of shrimp...

            It's probably a survival mechanism - when the environment is sub-optimal, more females to increase population numbers when they improve. When just right, more males to give females more choice I.e. allowing female selection to improve hereditary traits.

            Ain't nature fascinating!
            Thanks for all the fish!


            • #7
              Yup, I went hunting once and found some biology papers from the 60s where they were experimenting with temperature and guppies, and they found it skewed the ratios with higher temps resulting in more males and lower temps with more females.


              • #8
                Crocodiles sex ratios are influenced by temperature of the eggs in the nest. I have heard that temperature and pH influences sex ratios in fish.



                • #9
                  Apistogramma sexes are also affected by temperature. Apparently the sex is set in the first two weeks of life. 26 degrees should see a 50%-50% mix, while 24 will be skewed towards females and 28 will be skewed towards males.


                  • #10
                    So if the effects of temperature are sorted ie. higher temps = more males, Lower temps = more females
                    Does anybody know which way higher or lower pH swings things? Or does this depend on the type of fish?
                    From memory I kept my endlers at lower pH, approx 6.5 and my mates tanks would be around 7.4, I had more males he had more females.


                    • #11
                      In Uwe Romers fabulous book on Dwarf SA cichlids there is a huge section on sex determination.It varies in Apistos as to whether they are pH or temperature dependent or both.For most Apistos higher temp produced more males and lower pH more males.For some eg njisseni temperature had a profound effect,but not pH .I raised a batch of njisseni at pH 23 C at pH 4.5 and got almost no females.A.caetei is the opposite;temperature had no effect but pH a huge one
                      In some killifish (SA annuals) overcrowding produces a skewed ratio
                      There has been discussion on the rainbow forums about skewed ratios in this fish but Ive not experienced them


                      • #12
                        That's excellent,thanks killiguy.

                        Thought I'd also have a bit of a look on the net
                        Found this article from TFH magazine. Pretty interesting read.



                        • #13
                          Guppies under certain conditions can change se but I can't remeber where I saw the article. If I find it I'll post it.
                          If practice makes perfect and nobody's perfect then whats the use of trying?


                          • #14
                            answer: yes. it does affect fry of some species.


                            take a look at this article.
                            it should explain most basic reasons how temperature or environmental factors may affect fish sex.
                            any more detail you will need a science degree to better understand it.
                            Last edited by sharkwater; 10-12-10, 12:40 PM.


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