• Hello guest! Are you an Apistogramma enthusiast? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's a great place for Apisto enthusiasts to meet online. Once you join you'll be able to post messages, upload pictures of your fish and tanks and have a great time with other Apisto enthusiasts. Sign up today!

Sex ratios and temperature

Ttw

Active Member
5 Year Member
Messages
219
Location
Goodyear, Az. USA
I am aware of the effect of temperature on sex ratios. However, there seems to be some confusion, maybe just in my mind, about whether the temperature effect is when the eggs are laid or the temperature in which the fry are raised. What is the current thought?
 

Mike Wise

Moderator
Staff member
5 Year Member
Messages
11,202
Location
Denver, Colorado, U.S.A.
According to Römer & Beisenherz (1996) sex determination occurs over the first 6 weeks post-spawning. So ideally one should breed and keep the eggs/fry at the preferred temperature for at least 6 weeks. Since it occurs over a long period, one should be able to take eggs/newly freeswimming fry from higher/lower temperatures and raise them at the preferred temperature and still get close the the sex ratio you want. I don't know if this actually works; maybe a good graduate thesis?
 

Frank Hättich

Well-Known Member
5 Year Member
Messages
563
Location
Germany
That's interesting, because in his "Cichlid Atlas", Vol. 1, Römer says that merely the first 25 days after spawning are relevant for sex determination?!
 

wethumbs

Active Member
5 Year Member
Messages
476
The 600hrs (25 days) is a simple estimation of his data set. It is not exact at all. His data set was also limited to only a few species. Study the graphs on p.153 and 154 and you will understand (or maybe not).
 

Frank Hättich

Well-Known Member
5 Year Member
Messages
563
Location
Germany
I have studied the graphs and I think I understood them quite well. But this isn't the point here. The point that drew my interest is that Römer himself concludes in the Cichlid Atlas text that the graphs show that the relevant period is 600 hours, whereas the paper Mike has cited seems to say that the period is much longer. Since the Cichlid Atlas is published in 1998, it's safe to assume that Römer knew his paper from 1996 (the german version is even from 1995) and that the conclusions from that paper will probably not be based on better data from more species than the later published text in the Cichlid Atlas. So if this paper says the relevant period is significantly longer than 25 days, my question is simply what is the correct conclusion from his work/data? Of course, normally one would assume that the later one is also the better founded one, but if this isn't the case here, I would be interested why?
Moreover, the maximum length of the relevent period that one could possibly read from the graphs is imo 850 hours = 36 days. And ths is still much shorter than 60 days.
 

Mike Wise

Moderator
Staff member
5 Year Member
Messages
11,202
Location
Denver, Colorado, U.S.A.
Personally I don't really care whether it is 24 or 42 days. When in doubt, pick the more conservative (longer) period.:) I keep my breeding tanks (the fish room, actually) at a constant temperature and don't worry about it.
 

gerald

Well-Known Member
5 Year Member
Messages
1,491
Location
Wake Forest NC, USA
The sex organs might become differentiated into either testes or ovaries at different ages in different individuals, based on interaction of many different environmental and socially-influenced factors. Anybody who has raised aquarium fish, whether cichlids, livebearers, tetras, rainbows,or other fish, has seen "early-bloomers" and "late-bloomers" that show visible sex characteriistcs at widely different ages, from a few weeks to several months. Presumably the sex determination of the gonads (which must happen before or during the outward changes) can also occur over a prolonged age range. I would follow Mike's advice and go with the longer period. Has Romer or anybody else done any further CONTROLLED experiments on this after the early 1990s work? And do other cichlid groups (e.g. Pelvicachromis & Nanochromis) follow a temperature & age effect pattern similar to Apistos?
 

Tph

New Member
Messages
10
it seems the study of Romer is the only one for Apisto (kind of strange... or the study had so much impact it became definitive):
"In the genus Apistogramma (South American Cichlids),
TSD was demonstrated in many species and thus also seems well
established, although the evidence gathered so far originates from a
single study" (Ospina-Alvarrez&Piferrer, 2008)
see more here:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002837
 

gerald

Well-Known Member
5 Year Member
Messages
1,491
Location
Wake Forest NC, USA
Thanks for posting that link. Albert So reported in the Nov-Dec 2012 issue of Cichlidae Communique (Pacific Coast Cichlid Assoc) that his wild-caught pair of Pelv. taeniatus Moliwe produced 3/4 females at 73F, 1/2 females at 79F, and 1/4 females at 85F, with pH 6.5 to 7.0 and conductivity around 150 uS. Sex became apparent externally at about 6 weeks old at 79F; he didn't specify age of sex determination for the higher and lower temps.
 

rr16

Active Member
5 Year Member
Messages
536
Thanks for posting that link. Albert So reported in the Nov-Dec 2012 issue of Cichlidae Communique (Pacific Coast Cichlid Assoc) that his wild-caught pair of Pelv. taeniatus Moliwe produced 3/4 females at 73F, 1/2 females at 79F, and 1/4 females at 85F, with pH 6.5 to 7.0 and conductivity around 150 uS. Sex became apparent externally at about 6 weeks old at 79F; he didn't specify age of sex determination for the higher and lower temps.

Did he repeat breeding them at the different temperatures? If each sex ratio at each temperatutre is based on only one spawning then this is evidence of the temperature effect in this particular pair of individuals of this species, but would require further studies and the results should be replicable to ascertain any kind of pattern.

There are just so many interesting studies that could be done, but need people to do them for free (graduate projects or scientifically-minded hobbyists with fish rooms), or else need money to fund them.
 

mixmixi

Member
Messages
82
This is a very unreliable practice in my opinion. Even if studying a species and concluding by raising the temperature, the number of female decreases, could this be applied for a higher or lower tds? pH? I would tend to not rely on an individual study as a conclusion...
 

rr16

Active Member
5 Year Member
Messages
536
I seem to remember reading somewhere that pH or other factors tends to have a correlation with sex ratios too. Again, correlations don't always equal cause, but who knows. No idea where I read it or how reliable it was though.
 

wethumbs

Active Member
5 Year Member
Messages
476
Dr. Romer used Design of Experiments (DOE) for his studies. DOE is widely used in engineering, pharmaceutical, and many other areas of applications. He used 2 factors interactions (temp. and pH) for his experiments with CSS-Statistica statistical software to do the analysis. I personally used a different software (JMP) but the resulting tables, graph, charts are similar. The software is basically a tool, it still requires a 'trained' individual with a certain level of statistical knowledge to interpret the data and come up with a conclusion. I would not be surprised if he got help from someone in the math department when he was working towarded his PhD.

P.146 of the Cichlid Atlas I shows the interaction plots of 7 different species of Apistos. As the plots indicate, some are influenced by temperature to varying degrees while others are more by pH. It is also interesting to see that at certain temperature, pH interaction on sex determination becomes negligible for some species.
 
Last edited:

rr16

Active Member
5 Year Member
Messages
536
Dr. Romer used Design of Experiments (DOE) for his studies. DOE is widely used in engineering, pharmaceutical, and many other areas of applications. He used 2 factors interactions (temp. and pH) for his experiments with CSS-Statistica statistical software to do the analysis. I personally used a different software (JMP) but the resulting tables, graph, charts are similar. The software is basically a tool, it still requires a 'trained' individual with a certain level of statistical knowledge to interpret the data and come up with a conclusion. I would not be surprised if he got help from someone in the math department when he was working towarded his PhD.

P.146 of the Cichlid Atlas I shows the interaction plots of 7 different species of Apistos. As the plots indicate, some are influenced by temperature to varying degrees while others are more by pH. It is also interesting to see that at certain temperature, pH interaction on sex determination becomes negligible for some species.

Ooh, sounds interesting. Perhaps I should invest in this Atlas! I hate statistics, but like diagrams! Maybe I could get a PhD in something like this!
 

dw1305

Well-Known Member
5 Year Member
Messages
2,755
Location
Wiltshire UK
Hi all,
I don't know if there are any other published studies, or even if hobbiests have there own data for pH, temperature and sex ratio, but if this data were available it would be possible to conduct a meta analysis on this which would give approximate confidence intervals for the effect of pH and temperature (and their interaction) on gender.

We use "R" <http://www.r-project.org/> for this sort of work, which has the advantage of being open source soft-ware <http://www.jstatsoft.org/v36/i03/paper>.

cheers Darrel
 

BigTom

New Member
Messages
10
It's great once you've got scripts for everything you want to do, but I hate learning new packages. I am terrible at scripting in general however.

It probably didn't help that the last package I had to learn (rMark) has a manual called 'A Gentle Introduction...' which is 1000+ pages. I guess that isn't really R's fault though.
 

wethumbs

Active Member
5 Year Member
Messages
476
It reminds me of the RS/1. Personally, I prefer SAS, is like working with MS DOS versus Windows.
 

Members online

Forum statistics

Threads
17,915
Messages
116,200
Members
13,027
Latest member
tonc61

Latest profile posts

Josh wrote on anewbie's profile.
Testing
EDO
Longtime fish enthusiast for over 70years......keen on Apistos now. How do I post videos?
Looking for some help with fighting electric blue rams :(
Partial updated Peruvian list have more than this. Please PM FOR ANY QUESTIONS so hard to post with all the ads poping up every 2 seconds….
Top