hi there,
i have got a question concerning sex determination in elassoma species since many keepers of these little guys (at least here in germany) have problems with sex ratios in their raised offspring (in most times much more male fish occur).
Are their any data how sex determination is managed in elassoma species? how is the sex ratio in wild life habitats? some people here argue with temperature but in my eyes it is not very convincing. are centrarchid fishes known to have a genetic sex determination? might other influences like availibility of food or anything else cause changes in ratios of both fishes?
kind regards
torben
elassoma sex determination
Started by
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, Feb 05 2012 05:13 AM
14 replies to this topic
#2
Guest_EricaWieser_*
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Posted 05 February 2012 - 10:47 AM
Are you positive that the sex ratio is skewed? Sometimes it's hard to see the females because they can go hide in the plants. To really know how many fish are in there you'd have to empty the tank. About a year ago when I moved I thought I had a few dozen of Elassoma but found out after draining the tank that there were 84 or something ridiculous like that. They hide very well in the plants.
Edited by EricaWieser, 05 February 2012 - 10:50 AM.
#3
Guest_skalartor_*
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Posted 05 February 2012 - 02:32 PM
hi,
thanks for your answer. I for my person never had this problems in that way but many other elassoma-keepers here told me about that problem. and what is definitively true is that e. boehlkei/alabamae/okatie populations here in germany broke down because of lacking females. i think that is a quite strong indication for this problem.
torben
thanks for your answer. I for my person never had this problems in that way but many other elassoma-keepers here told me about that problem. and what is definitively true is that e. boehlkei/alabamae/okatie populations here in germany broke down because of lacking females. i think that is a quite strong indication for this problem.
torben
#4
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Posted 05 February 2012 - 03:09 PM
It's a strong indication of a problem existing, but not necessarily of that specific problem. There could be a lot of things going on. For example:hi,
thanks for your answer. I for my person never had this problems in that way but many other elassoma-keepers here told me about that problem. and what is definitively true is that e. boehlkei/alabamae/okatie populations here in germany broke down because of lacking females. i think that is a quite strong indication for this problem.
torben
1. Females are born but later die, for example by getting beaten to death by males
2. Females hiding all the time and the eggs not surviving to maturity leading to dying out of species and you thinking there weren't any females
If you had asked me a few days ago I would have answered that my current batch of fry was all males. But this very morning five cute little baby females came out to eat. They are the same size as the cute little baby male but much shyer. They only came out from the plants for the first time ever because they felt safe in a group.
I would like to talk one on one with the people who are actually having this problem. I want to know what tanks mates, substrate, plants, temperature, type of food, and pH and DH their tank has. There could be a lot of things leading to the dying out of the species, even something as simple as pea gravel (the fry get stuck in it). And I want to know if the perceived lack of females is backed up by them draining the tank and counting the fish.
Edit: Sorry if I sound kind not-believing. I do believe that it could happen; there are strains of Xiphophorus hellerii in the Genetic Stock Center that occasionally throw all one gender batches of fry. It's just that recently people have been hammering into my brain to make sure the experiment is going wrong in the way you think it is before you spend weeks correcting the wrong problem. heh heh.
About two months ago I remade the RNA for a PCR and re-ran it six times only to find out after running out of the fluorescent marker and using a new bottle that it suddenly worked. XD Sometimes what you think is wrong isn't actually the problem. And before stressing out and trying over and over to fix the 'problem', you've got to be sure that's what's really going wrong. There could be multiple things resulting in the disappearance of females in this situation.
Edited by EricaWieser, 05 February 2012 - 03:22 PM.
#5
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Posted 05 February 2012 - 03:17 PM
actually all the points you mention are worth having a thought over them. i had the same idea about dying females but had no hint for this.
but the guys that were dealing with these rare elassoma species were (and probably are) real experts on these fish. they are authors of scientific articles about elassoma species and i think they knew what they were dealing with. and since many people told me about this problem, i thought it would be a good idea to talk to some people from (or at least near) their native habitats.
kind regards
torben
but the guys that were dealing with these rare elassoma species were (and probably are) real experts on these fish. they are authors of scientific articles about elassoma species and i think they knew what they were dealing with. and since many people told me about this problem, i thought it would be a good idea to talk to some people from (or at least near) their native habitats.
kind regards
torben
#6
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Posted 05 February 2012 - 03:26 PM
Have you asked Gerald? Recently he asked me for some females because his had all died out.actually all the points you mention are worth having a thought over them. i had the same idea about dying females but had no hint for this.
but the guys that were dealing with these rare elassoma species were (and probably are) real experts on these fish. they are authors of scientific articles about elassoma species and i think they knew what they were dealing with. and since many people told me about this problem, i thought it would be a good idea to talk to some people from (or at least near) their native habitats.
kind regards
torben
Edit:
And I found this while googling which you may be interested in: http://www.nanfa.org...may06/0153.html
...Elassoma evergladei spawns in my water(ph around 7.5 GH/Kh round 8 ) and the sex ratio is pretty even(need to find out how to curb male aggresion or know when to remove females as I lost maybe 2 this season to males).
Edited by EricaWieser, 05 February 2012 - 03:30 PM.
#7
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Posted 05 February 2012 - 03:36 PM
Oh wow. Daniel B. from http://www.aik.it/fo...php?topic=318.0 is reporting an offspring sex ratio of 60 males to 3 females.
I've had Elassoma gilberti spawn in even sex ratios in two setups:
One, at pH 7.5 DH 16-20. Even sex ratios. Unheated tank, room temp was in the 70's F.
Second setup: pH 6.5, DH 0, unheated tank at 65-75 F. So far there are five little baby girls to one very dominant baby boy; their genders still aren't 'fixed' and they're just now getting large enough to come out in the open so I'll find out soon. But yes, there are definitely some female offspring.
I have fine grain substrate so the eggs can't get stuck in between the rocks. Currently kitty litter. For a few months it was sand in the 10 gallon, but it's been pure clay kitty litter for years now.
That's ridiculous; my fry have never done anything like that. Wow.Putroppo la sex-ratio è squilibratissima e le schiuse “all males” cioè 60 maschi e 3 femmine non sono rare.
I've had Elassoma gilberti spawn in even sex ratios in two setups:
One, at pH 7.5 DH 16-20. Even sex ratios. Unheated tank, room temp was in the 70's F.
Second setup: pH 6.5, DH 0, unheated tank at 65-75 F. So far there are five little baby girls to one very dominant baby boy; their genders still aren't 'fixed' and they're just now getting large enough to come out in the open so I'll find out soon. But yes, there are definitely some female offspring.
I have fine grain substrate so the eggs can't get stuck in between the rocks. Currently kitty litter. For a few months it was sand in the 10 gallon, but it's been pure clay kitty litter for years now.
Edited by EricaWieser, 05 February 2012 - 03:45 PM.
#8
Guest_skalartor_*
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Posted 05 February 2012 - 04:12 PM
thanks for your efforts.
but that is exactly what i am thinking about at the moment. how can it be that sex ratio is so different among different breeders. as i told you i never had to many problems with sex ratio of my offspring. but there are many people telling the same stories of much more males then females in their f1 generation. i don't know whether this can be caused by several aspects (chemical, physical, behavioural, biological) or whehter there is one key factor.
right at the moment i try to encourage everyone dealing with these lovely species to have a detailed look at their spawning conditions to be able to see which parameters are might affect this topic.
torben
but that is exactly what i am thinking about at the moment. how can it be that sex ratio is so different among different breeders. as i told you i never had to many problems with sex ratio of my offspring. but there are many people telling the same stories of much more males then females in their f1 generation. i don't know whether this can be caused by several aspects (chemical, physical, behavioural, biological) or whehter there is one key factor.
right at the moment i try to encourage everyone dealing with these lovely species to have a detailed look at their spawning conditions to be able to see which parameters are might affect this topic.
torben
#9
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Posted 06 February 2012 - 12:35 PM
I have had skewed sex ratio problems with softwater cichlids, killifish, and anabantoids, but never with Elassoma gilberti -- the only pygmy I have kept for multiple generations. I ran out of females by thinking I had more than I really did, and giving them away, not because of sex ratio problems. Erica's females got me going again :>) My water is very soft and pH fluctuates a lot between high-5s to low-7s depending on my water changes (or lack of). I have bred them indoors and outside, and the outside tanks temperature fluctuates between 50 and 90 F (10 to 32 C). So I doubt whether E. gilberti sex is strongly affected by temp or pH.
Not enough food can certainly cause excess males, since the females seem to be less aggressive competitors and grow slower.
I suppose it is possible that environmental sex determination might be more sensitive in E.boehlkei and okatie, endemic to blackwater habitats. The other species (gilberti, okefenokee, zonatum) occur in both blackwater swamps and limestone-based streams. With tropical fish, it seems to be mostly species from soft-water habitats that are generally more sensitive to environmental sex determination.
Not enough food can certainly cause excess males, since the females seem to be less aggressive competitors and grow slower.
I suppose it is possible that environmental sex determination might be more sensitive in E.boehlkei and okatie, endemic to blackwater habitats. The other species (gilberti, okefenokee, zonatum) occur in both blackwater swamps and limestone-based streams. With tropical fish, it seems to be mostly species from soft-water habitats that are generally more sensitive to environmental sex determination.
#10
Guest_skalartor_*
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Posted 07 February 2012 - 12:26 PM
hi,
thanks for your answer.
i think it is an reasonable hypothesis that fish occupying softwater habitats are more sensitive to environmental changes as far as sex ratio is concerned. the lack of many minerals in this water as well as carbonate allows more and heavier fluctuations than carbonate buffered waters. the question in general stays what parameters cause such fluctuations in sex ratio (i still think that at least under some tank conditions this is a true phenomenon). there are many things that could be imagined and many different influences appear important for other fish species. but what is actually important for elassoma?
torben
thanks for your answer.
i think it is an reasonable hypothesis that fish occupying softwater habitats are more sensitive to environmental changes as far as sex ratio is concerned. the lack of many minerals in this water as well as carbonate allows more and heavier fluctuations than carbonate buffered waters. the question in general stays what parameters cause such fluctuations in sex ratio (i still think that at least under some tank conditions this is a true phenomenon). there are many things that could be imagined and many different influences appear important for other fish species. but what is actually important for elassoma?
torben
#11
Guest_cosmictwang_*
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Posted 12 April 2012 - 05:35 PM
I hate to bump really old threads, but I've had that problem too. I raised a few batches of elassoma fry and for the first set, they were mostly males, I think out of 11 fish, there were 3 females. They were hatched sometime in october, and I didn't use a heater. I have no idea what the temp was on them.
I raised a pair from that generation and bred another three sets of fry. This time I did use a heater set to 80, and left the fry in the tank with the adults until they stopped hanging off of plants. I took them out and left them in a fish bowl for another week. Then, I put them in a larger tank, which also had a heater set to 75.
When I went to pull the oldest generation out of my fry-raising tank so I could continue using the tank to raise fry, I noticed that I don't see a single male, out of the dozen almost 3/4" females. Worse, I don't see a male in the younger fish either. All the fish were raised in the same water, fed the same thing, and born in the same tank. I always do weekly 60% water changes. If anyone has any suggestions, I still have a batch of very young fry left to play with. There's definitely something odd going on.
I raised a pair from that generation and bred another three sets of fry. This time I did use a heater set to 80, and left the fry in the tank with the adults until they stopped hanging off of plants. I took them out and left them in a fish bowl for another week. Then, I put them in a larger tank, which also had a heater set to 75.
When I went to pull the oldest generation out of my fry-raising tank so I could continue using the tank to raise fry, I noticed that I don't see a single male, out of the dozen almost 3/4" females. Worse, I don't see a male in the younger fish either. All the fish were raised in the same water, fed the same thing, and born in the same tank. I always do weekly 60% water changes. If anyone has any suggestions, I still have a batch of very young fry left to play with. There's definitely something odd going on.
Edited by cosmictwang, 12 April 2012 - 05:43 PM.
#14
Guest_gzeiger_*
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Posted 14 April 2012 - 08:31 PM
I had this problem while trying to raise Gambusia affinis. There was some literature suggesting temperature dependence in that species, but I wasn't able to duplicate their results in my tanks - always ended up with far more males.
In the wild it seemed like I generally caught slightly more females than males. I didn't make any effort to determine sex of immature fish, nor keep any kind of count, so this is really just my impression, but it seems like I've almost always caught males in pairs (a male and female in the same net scoop), while I sometimes find single females.
In the wild it seemed like I generally caught slightly more females than males. I didn't make any effort to determine sex of immature fish, nor keep any kind of count, so this is really just my impression, but it seems like I've almost always caught males in pairs (a male and female in the same net scoop), while I sometimes find single females.
#15
Guest_EricaWieser_*
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Posted 14 April 2012 - 08:35 PM
Very understandable if you've ever watched livebearer social interaction. I recently found a perfectly healthy young female guppy dead in a tank with twice as many males as females. The males will chase females around, nipping at her and really being an annoyance. Any situation where two males have settled upon one female results in her struggling to get out of there as fast as she can.it seems like I've almost always caught males in pairs (a male and female in the same net scoop), while I sometimes find single females.
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