question about sex ratio

zapisto · Post by **zapisto** » Tue Feb 14, 2006 11:17 am

as i say before i am a breeder of apistogramma.
with apistogramma the temp/PH impact on the sex ratio.

what will be the parameters who impact shrimp sex ratio if any do ?

TKD · Post by **TKD** » Tue Feb 14, 2006 5:50 pm

Bonjour,

With small shrimp like your Tigers it does not matter... think of them as tetras or schooling fish were sex ratio does not matter.

TKD

badflash · Post by **badflash** » Tue Feb 14, 2006 7:12 pm

I don't know that there has been a serious study of this by any of our members. I know with Endlers Guppies cold temps favor males and hot temps favor females. I'm keeping my cherries at 78F. I'll see if there is any change over 50/50 with this batch of shrimp. I'm moving the wild types to a tank that is at 70 degrees. We'll see if it matters.

zapisto · Post by **zapisto** » Tue Feb 14, 2006 8:50 pm

TKD wrote:Bonjour,

With small shrimp like your Tigers it does not matter... think of them as tetras or schooling fish were sex ratio does not matter.

TKD

hi
it is not problem of matter
just a case of study

when i am doing something i usually go deeper then general

for now i am beginner so i cannot even thinf of testing this but can be interesting to know
but even with tetra you have an alchemy between parameters who impact sex ratio

Post by **Mustafa** » Tue Feb 14, 2006 11:42 pm

There is really no official study or even hobbyist observations on sex ratio with shrimp that I am aware of. The major issue with conducting such observations is that most people keep shrimp in groups of 10 or more. It's kind of hard to keep track of offspring of any given female in such a group. Later the group grows, some shrimp die, some young grow up and produce more young..in other words it's just one big "mess."

To really test the sex ratio one would have to set up several separate tanks with, say, different PH levels in each tank and put only one male and one female shrimp in each tank. Then one would have to count the males and females in every tank once the offspring mature. To be sure one would have to repeat such an experiment several times. Considering that shrimp take about 2-3 months to mature (on average) this could take a very long time. Not undoable, though. I'm sure it will be done at some point, especially once shrimp are more common in aquaria then they are now.

badflash · Post by **badflash** » Wed Feb 15, 2006 3:21 am

If it is anything like several other species, the strongest influence on sex ratio would be temperature. pH may effect the # of shrimp produced more than any effect on sex ratio.

Why don't we just poll the group and see if those who are getting lots of babies are getting more males or females, or an even mix and what their conditions are for things like pH and temperature, hardness, etc. What we would be looking for is something obvious, like 5:1 one way or the other like I've seen in Endlers.

Post by **Mustafa** » Wed Feb 15, 2006 6:49 am

badflash wrote:If it is anything like several other species, the strongest influence on sex ratio would be temperature. pH may effect the # of shrimp produced more than any effect on sex ratio.

Both temperature and ph have been reported to influence sex ratios in certain dwarf cichlids. Here is one of many such reports:

http://www.cichlidae.com/article.php?id=100

The most famous example is the "krib" (Pelvicachromis pulcher), but ph influence on sex of offspring has been reported in Apistogramma, too. "Zapisto" says he's a dwarf cichlid (Apistogramma) breeder, so that's where got the idea from. With shrimp we just don't know yet and everything is just speculation until we have some experimental proof.

Maekellen · Post by **Maekellen** » Wed Feb 15, 2006 11:51 am

A better sequence of tests though would be to test one variable at a time. Set up the seperate tanks with the exact chemistry and run a battery of tests, using different male/female pairs each time, with just the temperature different.

Then, rerun the battery of tests, but vary the pH in each tank and use a constant temperature.

By using a different male/female pair for each test, you have a better species test. Otherwise, it would be indicative of the individual shrimps tested, which would lean towards suggesting the same influence on the species, but would not be even inconclusive proof.

Seperating the test parameters to test only one variable at a time ensures accurate data. You will know if it's the pH or the temperature variation that is influencing the offspring. Or any other water parameter you're testing for influence from.

Then, you get several others interested in either breeding, or simply the knowledge of environmental sexual determinants in captive bred shrimp to do the same tests you did and compare results.

badflash · Post by **badflash** » Wed Feb 15, 2006 1:43 pm

Yea, but I want to raise shrimp, not conduct experiments. Before you go to all that trouble wouldn't make sence to see if there was any gross effect? Once you see if there is SOMETHING skewing the male/female ration you could then refine it and see what it is.

Anyone notice if theyhave more males or more females from their fry?

Maekellen · Post by **Maekellen** » Wed Feb 15, 2006 2:33 pm

Simplest way to test for gross defect would be to set up three seperate hatchery tanks with same initial water parameters, same plants, same substrated and identical deco, but with a 2-4 degree temperature difference between each tank, for a total spread of 4-8 degrees. Put in your test mating pairs and do water chem tests daily.

Repeat twice and you should have enough data to conclude whether or not there is a gross effect somewhere. The water chemistry for each tank should end up sith a slight variance on its own.