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I am a little bit wondering now. I have P. harveyi and have had it for some time, – this is one of the species I really want to continue to have so I try to have as many breeding pairs as possible. At the moment I have 3 pairs separated.
They seem to do well, – I dont breed intensively, but from the last succesfull spawning there has been about 10-12 fry growing up.
But I have a problem which seems to continue, – this is the second pair and the second time in which a spawning turns out to be mostly males. I really have to search and be lucky to find one or two females in a spawning of 12.This does not happen with the other species I have. I have fry of p.parvulus and p.nagyi and here its about 50/50 or at least much more balanced.
The conditions – water, food, temperature is the same.Do you have any ideas what could cause this, and if I should try to alter something what should I alter ?
Ph is around 4.5 – 5 – microsiemes is very low, I use pure RO water, and I use this german product ‘eichenextract’ to lower ph. It does highten the microsiemens a bit but it doesnt seem to be a problem with either of the other species, and it doesnt seem to be a problem f.instance with parvulus breeding.
I thought I would try to alter one factor with the harveyis in order to see if I could change the unfortunate ratio of too many males, – but I am unsure which factor would be the best to start with ???
Its a bit unfortunate to continue to have a growing population of p.harveyis when they are all males 🙁
Dear Helene, sorry to say but this is a very common experience many breeders have to endure. And mostly there is no explanation for it. There have been broods with 6o nagyi, all female. Or broods with 70 linkei, all male and only two or three female.
All or nearly all environmental factors could play a decisive role in finally fixing the sex of a young fish developing from a larvae to ab age of about two or three months. We know that for instance pH, temperature and the content of humine substances coud affect the sex ratio of the very young fish. But we cannot say definitely which is responsible in a certain case except there is some really borderline value indicating that it is probably the causer.
Did you control temperature? Was it especially high or low? Have you been conscious about the amount of humic substances? P. harveyi is especially bound to the typical blackwater conditions, more than nagyi or linkei or spec. Sentang, not to speak of paludicola. It will spawn at several pH-stages (all well below 7.0) but all of these are compatible with more or less shares of humine acids. We also know that typical blackwater-fish (just as harveyi) do often spawn in clearwater, too, and we do not know to which effect.
At any rate, I use that “Eichenextrakt” too, but I am not sure that it contains the same qualities in every charge. To my knowledge it does contain little “Eiche” (oak) but much phosphoral acid. It must be manufactured cheaply. Nevertheless I am rather content with it in most cases.
But I am not sute that this is the cause of your one-sex-experience. Without heavy experimenting we will not solve the riddle. Sorry, but youz are memmber of a big community of experinenced breeders woho all share your problems and – in the end – don’t know what the reason is…
Then I wonder … were those people who experienced it able to change it ? Did they manage to get more balance I wonder.
I will try something.
The temperature is in between, its definitely not high, no heater involved. Just in a room with room temperature, and this is around 22-24.I have to try to understand this with the humic acid a bit better then. I have not paid more attention to it than in any other tank.
I am not sure how to change this however .. or control it.No, I do not kwow of anybody who was experimenting that strict and comprehensive as it would have to be done in order to get clear and stable results. And I know many good breeders who had the same problems, in fact nearly all (Walther Foersch, Willi Harveyi, Allan Brown, Horst Linke, Günter Kopic, Martin Hallmann, and others). No aquarist has a laboritory and the time to start seriously an experimental series on this.
But I know some scientists who have done research on the question of the development of sex in fishes and other animals who do not fix it in the moment of fertilization. But to my knowledge all they have found out is the relationship to those environmental factors, and not how to influence it quatitatively by experiment. I do not know of any rows of results indicating that e.g. such an increase/lowering of temperature results in such quatitative a change of the sex ratio. But I shall try to contact them and ask. One of them is a German colleague from Berlin; maybe he knows more.
But I doubt it. When he put forward his results in lecture I heared and in an article I read, he was concentrating on the necessity of humic substances für blackwater organisms. He proposed to use oak and beech leaves, but there was no statement on quantity. So I presume that all these findings are results of qualitative research and not of quantitative research. But I shall ask him.
🙂 no, I was also not thinking of starting a serious investigation in a scientific way 🙂 .. but if there was something I could do I would really try.
But its good to hear that I am not the only one that experienced this and maybe I should be happy that I do have at least a few females now and then.But I am a bit curious .. so, its not particular species this happens to ? Its not that p.harveyi is more in risk of this than others ?
It just happens that in my tanks its p.harveyi that has this problem ? or is it often p. harveyi ?
Just wondering ..No, as far as I know there is no indication that this phenomenon is more often observed in P. harveyi than in other species. You could ask Martin Fischer or Bernd Bussler who both are good breeders of this species and did raise several bigger broods each.
The most cases of a single sex in a brood that I know of were observed with nagyi. But in one case (me) it was (nearly) only females, in the other (Hallmann), only males, nearly. Günter Kopic info(at)guenter-kopic.de has a lot of experience in these things.
Thank you, maybe Martin will see this postings ..
In my case I can say that it is not just in one brood, it is now continually and not just with one pair but it seems with more pair … hmm… however come to think of it, it is actually the same female, – and of course same ‘stock’.
Hello, Helene,
I have heard about this phenomenon before in other fishes. In Dario dario the sex of the young is obviously influenced by temperature and water hardness. I had no time to search thoroughly now, but I found something here:
warmer: more males, cooler: more females
softer: more females, harder: more malesConcerning the humic acids and the organic load of the water I recently had similar questions at the IGL-Forum – which splitted a thread and created confusion (which was not my fault!!). The result was a very interesting thread with extensive thoughts about black waters. I’m afraid it’s all in German (but that’s no big problem for you, I suppose)
Hello everybody,
this is a very interesting topic indeed. I have more or less the same water conditions in every tank: small bag of peat granules; beech leaves and a piece of Catappaleave; around 23°C;
With P. harveyi I get very balanced sex ratios up to now. With some Betta on the contrary, I always have a lot more males.I tend to agree with Richard Brode (IGL), who states that this could be a general problem of extensive breeding: males grow faster, are more aggressive and therefor get more food. So they starve out the females in a very early stage (which one doesn’t realize) and you end up with all males.
It would be interesting to hear if someone who breeds intensively, really gets well balanced sex ratios.
Greets
MartinThank you Stefanie for the links, – I have seen the thread you are mentioning, unfortunately yes, it is impossible for me to really understand.
Martin, – thanks also for answering. Its an interesting theory, –
But also for me its the same conditions in all tanks, – and I have 8 species, only with the harveyies is the problem.And I might breed extensively 🙂 but I feed ‘intensively’ .. meaning I probably way overfeed, – would that not help this problem. Unless its in the very early stages as you say before the fry take any artemia.
I certainly will be aware of it in some way.
Hi Helene,
I know from breeding appistos, skewed sex ratios was mostly caused by temperatures. Since your tank is unheated it may be caused by tempurature fluctuations, maybe by just adding a heater to stabilize may solve the problem. Of course cooler water is a longer developement time and warmer water is faster. Which makes more males or more females I can’t remember. (I believe warmer makes more males but not sure anymore)
I realize appistos and Paros are a world apart, but both share the exact same sex ratio problems, including soft, acid and usually black water prefered systems.
Thank you all, its really interesting, – 🙂
I could now set up 3 tanks trying out
1. stable temperature (sounds quite interesting, Ted)
2. really careful, intensive feeding of fry from very early
3. a tank with more fokus on humic acidityIts not much of a scientific experiment, but I will try tbem out, – anything that will change. I dont know what to keep doing with these ‘single’ male harveyis, I already have a 60 liter full of them 🙂
So something must be done.
But again, – it still puzzles me why only the harveyis and why all broods, not just once, but more times.
🙂 Cant help it … here’s some photoes of my young harveyi males. Playing around with the new camera, which has confronted me with another problem … how to clean the tank glass. I wasn’t aware that my frontglass was so dirty :blush:
Heres a little observation related to this problem :
I had this one pair of p. harveyi and they had quite a lot of fry swimming around in their tank, so I decided to take out some of the fry into another tank. They were quite big at the time, but before I could determine sex.
After some time it showed up that these were all males, and this was the reason I made this thread, because it really annoyed me that at whole tank now again showed just males 🙂
But then I started taking some of them out again into new tanks (because now I want to experiment a bit) .. and when I thought they were all out … :blink: … I found one small one, much smaller than the others .. and this one I think is female.And looking at the rest of the big brood – it does seem that after I had taken out the bigger ones, – more of the remaining seems to have a chance of being females. They are still not at all the same size as the first I took out (it could be more than one brood)
But it makes me think that there may be something about this with males being bigger, stronger and maybe ‘out-eating’ the smaller females. And maybe I did a good thing by – for other reasons though – separating some of the bigger fry out at an early stage.
Anyway, its just an observation ..
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