Sex RatiosI have a lot of issues with getting balanced sex ratios in my spawns. They tend to be very male heavy, which means I often have only a limited pool of females to draw on. Sometimes it seems that I am fortunate if I get any females at all. Wild bettas are only just starting to become more popular in Australia. However, as most hobbyists want a male/female pair to use for future breeding, I think it's going to be difficult to offload a large number of males to anywhere but my local fish store. My B. persephone spawn yielded only 6-7 females from at least 25 individuals. My B. uberis pair seem to have two female juveniles out of a total of five that I have seen, but they also have another 20 odd fry that cannot yet be correctly sexed. Currently my wild-caught B. burdigala pair have given me the worst results. I seem to have perhaps one female that I can find out of at least 20 individuals, and as this is still only a juvenile, I cannot be one-hundred percent certain. Fortunately, I have a confirmed female sub-adult and a possible three more females from my captive bred burdigala pair to make up for it. I just hope I am correct in my assumptions and they do not turn out to be late sprouters! I am starting to think that the temperature of my tanks is what is giving me so many more males. The coccina group of species, do not require excessively high temperatures, and yet I noticed that a lot of my tanks sit in the 27 °C range, which is equivalent to around 80 degrees Fahrenheit.
I am starting to think that this is much too hot. The tank housing my captive bred B. burdigala pair has the coolest water temperature out of all my tanks. They have also given me what appears to be the largest number of females. Therefore, when I do an overhaul of my tanks over the next week or so, I am going to be turning the temperature down to around 23-24 °C to see if this doesn't have an impact on ratios in future spawns.
Matthew
5/5/2013 09:39:01 am
Hmm... I agree that turning the temperature down might help. I know a lot of reptiles gender is temperature determined and theories have been tossed around that it affects the ratios in splendens to, so it's a common thing in nature... I think aiming for around the middle of their comfortable range would be ideal?
Ashlea
5/5/2013 10:18:46 am
Yeah I am probably going to only go down to around 24 degrees. I have kept and spawned them at this temperature in the past and there is some speculation that lower temperatures leads to a decrease in aggression. Comments are closed.
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AuthorLocated in Melbourne, Australia, I currently keep and breed a number of species from the coccina complex. Archives
November 2017
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