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inverted

Interesting ... But I'd think twice about turning your temp up to 28........ You'll also increase harmful bacteria too.

My 2 cents!

Edited by inverted
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revolutionhope

yep im shooting for 26 - 26.5 now.

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revolutionhope

they actually only tested 24,28 and 32.

. at 24 the shrimp had best longevity but took longer to reach maturity. ill have a good read tonight and share any other key points (if I can decipher more of the scientific jargon lol)

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kizshrimp

I'll have a look at the article later Will. 

 

The findings you report so far sound sensible. Not just with shrimp but other endothermic (eg. "cold blooded" animals) organisms the life cycle is highly temperature dependent. They will live longer at lower temps but breed quicker at higher temps. Killifish keepers are intimately aware of the effect of temperature. 

 

There were several mentions in the B&K magazines of breeding activity being affected by temperature but no mention of photoperiod being adjusted seasonally. As you would expect the breeding was reduced at low temperatures. One bee shrimp breeder allowed the tank temperatures to drop to around 15 degrees C for a couple of months during the winter and noted very high production rates as the temperatures were raised again. This is to be expected for temperate creatures such as these, who are supposed to experience seasonal temperature differences. The breeder above had determined that the increased productivity in spring outweighed the lost productivity during winter. 

 

I think it will be most useful and important to investigate the effect of pH and temperature on sex ratios in our shrimp, because some very useful manipulations could be achieved then. Something for people with enough tank space to consider testing. 

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revolutionhope

hey kiz thanks for the input!!

I notice im certainly getting a huge ratio of females to males in my endler tank. my endler tank is set to quite a low temp - I remember reading somewhere (albeit hobbyist /non scientific site) that higher temps equal more males with guppies. im overrun by females now but I dont want to raise temperature due to there being less dissolved oxygen at higher temp and the tank is stocked heavily. kind of a catch 22 hehe - most people dont want to take females from me they usually just want few males (good for nanotanks ofc) .. oh well lol!

ive never heard of ph being a factor on gender ratios but you've inspired me to do some searching on this subject once ive read up as much as I can on the above subject.

re the above study showing more ovigerous females at higher temps - ill have to clarify for certain if they mean more of the females were becoming fertile or there were just more females compared to males. I had thought it was the former but I was really tired last night.

I'm really looking forward to checking out these issues in more detail over the coming days. it kinda goes to show how much data is out there when one persists with searching. I had tried so many different search terms - I think one of the key words that helped me to get a lot more interesting links to studies was "physiology"

love n peace

will

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Disciple

Its a interesting read man. Thanks for sharing.

One thing i found interesting was that it says the growth increments was lower for the 24 degrees for the first 30 days but after that the shrimplets in 24 degrees caught up in the gi.

I remember there was a discussion about the effect of temperature here about 6 months ago. I believe it was jayc that links a graph showing the temperature and the average gustation period. The higher the temperature the lower the gudtation period.

Someone else mentioned in the same post how lower temperatures would result in more females while higher would give you more males. Ard 22 degree would give you more female and anything higher then 28 would result in more males . someone else said in their experience in aquaculture that in winter there would be more females too.

I know shrimpy daddy has said he believes keeping his shrimp at 26 degrees has given him the best results too.

Saying this are you aiming to find a temperature/conditions to keep the shrimp breeding all year round at as high rate as possible?

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revolutionhope

I've read the journal a couple of times now but going for a 3rd look soon :-)

i can see it very clearly states that 28 is optimum temp for breeding neos - but we do know that there is a higher risk of infection in high 20s. gender ratio data seems inconclusive/mixed between experiment 1 and experiment 2.

but the standout is their table shows the rate of fertile females at 28 is 100% and at 24 is much much less.

aside from risk of infection - longevity is reduced too. but from a breeding perspective the increased productivity would way offset this as long as you keep water conditions optimum and their immune systems aren't compromised.

anyone else have any inputon this? I can say for certain that since increasing my temperstures from 23-24ish up to 25-26ish im getting loads of new saddles and berries even though its only been a few days!

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fishmosy

I've had a quick look at the data and statistical analysis from the paper.

One thing to note is that the authors are writing from a perspective of commercial scale breeding. This means you (as a hobbyist) are going to want to grow your shrimp slightly differently. Keeping your shrimp at higher temps is almost certain to reduce their lifespan.

The authors suggest 28*C is best for breeding only because the shrimplets develop on the mother quickest and grow quickest at this temperature! This may be good for someone who is breeding them commercially, but what happens to the shrimp raised at 28 instead of 24? Do they die at 12 months rather than 18 months? Everything i've read points to shorter lives at higher temperatures.

The authors do not present data on how often each female got berried at each temperature. Hence we cannot draw any conclusions from the data about how temperature may affect how often shrimp breed. What is clear though is that there was NO difference in fecundity (the number of offspring) across the temperatures trialled (24, 28, 32). There was much lower survival of shrimplets at 32, but no difference between 24 and 28.

Final point is that the shrimp used in the paper were from one supplier in Argentina. the grade of the cherries wasn't stated. We know that higher grades tend to be less resilent than low grades due to inbreeding. Similiarly the shrimp found in Australia are likely to be slightly different from those in Argentina owing to the low nunbers of shrimp that were originally smuggled into Aus. Find what works best for you in your tank.

Edited by fishmosy

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revolutionhope

thanks heaps for having a look ben, can you tell me what it means by ovigerous females then and what those numbers mean in that table?

 

aside from the table data there is also this statement near the conclusion which leaves me pondering? -

 

"During the growth period, shrimps reached sexual maturity and mated, with the highest proportion of ovigerous females occurring at 28°C. All the females that matured and mated at 32°C lost their eggs, indicating a potentially stressful effect of high temperature on ovarian maturation. Based on high survival and good growth performance of shrimps at the three temperatures tested over the 90-day period it is concluded that N. heteropoda heteropoda is tolerant to a wide range of water temperatures, with 28°C being the optimum temperature for its culture."

Edited by revolutionhope

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fishmosy

Ovigerous means the shrimp were carrying eggs. So they kept the shrimp at 27, and once the females were berried, moved them to either 24, 28 or 32 *C, and then measured how long it took for the shrimplets to hatch, how many shrimplets were produced by each female, and what size the shrimplets were.

Then they did a second experiment where they grew shrimplets at 24, 28 or 32 to see which grew the fastest.

So because the shrimplets hatched and grew fastest at 28 compared to 24 or 32, they suggest 28 is best. This may be true for a commcerial farm where you want to sell the shrimplets as soon as possible so you want them to hatch quickly and grow quickly.

Assuming you mean table 1? Which numbers specfically?

Edited by fishmosy

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revolutionhope

yep table 1, the OF number. (attached)

 

im still not sure i understand why they would say the highest proportion of ovigerous females occurred at 28 degrees? my interpretation is that proportion means as a proportion of the entire female population that was kept at 28 degrees? but i don't have a science back0ground at all so im not too confident !

 

thanks again mate appreciate you taking the time to explain!

 

love n peace

 

will

 

-edit- the OF value is apparently "percentage of ovigerous females" - what does that mean?

post-1275-0-08053100-1431265345_thumb.pn

post-1275-0-08053100-1431265345_thumb.pn

Edited by revolutionhope

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fishmosy

Let me just check their methods again to see how they come up with that number (OF).

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revolutionhope

eagerly awaiting your response! :-)

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fishmosy

OK found it.

so as I said above they got the berried females, let them drop their shrimplets, and then grew the shrimplets on to see how fast they grew.

OF is the number of female shrimplets which got berried whilst the authors were measuring how fast they grew. There were 72 - 100% females berried at 28, whilst < 27% of females were berried at 24 or 32.

However I dont think this is proof that 28 is better than 24 for making shrimp breed. The shrimp at 28 were growing quicker than at 24, so would have matured quicker. Maybe most of the females at 24 were not yet sexually mature before the experiment finished.

The experiments were run for 90 days - three months.

Edited by fishmosy

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fishmosy

The way to work out which temp is best for getting shrimp to breed is to have a bunch of females with saddles, place them in (for example) 24 or 28*C, and then see how many mate and get berried. Of course controlling for how many shrimp get berried as a result of being moved from a different temperature would be difficult. Any breeding could be a result of a change in temperature rather than being at a specifc temperature.

All the anecdotal evidence indicates that higher temps (or a change in temp) stimulates breeding. The reason why I believe the aforementioned study does not provide proof about which temperature is best for stimulating breeding is because the authors were asking a different question - at what temperature do the shrimp grow fastest?

Edited by fishmosy
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revolutionhope

hmm im still nto convinced - it does state

 

"At days 30 and 60 of the Growth period of both experiments body weight was lowest, highest and intermediate (P < 0.05) in juveniles maintained at 24, 28 and 32°C, respectively. However, at day 90 this variable was similar (P > 0.05) among treatments (Fig. 3). The growth increment (GI) was significantly lower (P < 0.05) at 24°C than at the other temperatures tested over the first 30 days. This was completely reversed during the following 60 days, with the GI of shrimps at 24°C exceeding that of shrimps at 28 and 32°C (P < 0.05). At the end of the Growth period, GI was lowest, intermediate and highest (P < 0.05) at 28, 32 and 24°C, respectively (Fig. 4)."

 

doesn't this mean that over 90 days they all grew at the same rate over the 90 days, just that during the first 30 days the shrimplets grew faster at higher temperatures.

 

 

and -

 

"During the 90-day Growth period, the life cycle of this species was completed as evidenced by the fact that juveniles reached sexual maturity and mated. For this reason we consider that survival was good in all treatments, with maximum values obtained at 28°C in both experiments. This parameter tended to be lowest at 24°C when the embryo incubation temperature was 28°C (Exp. 2), further indicating a possible stressful effect of low temperature on shrimp performance."

 

"During the growth period, shrimps reached sexual maturity and mated, with the highest proportion of ovigerous females occurring at 28°C."

 

i've attached the table which im fairly sure shows that their bodyweight was the same by 90 days

post-1275-0-20690800-1431267359_thumb.pn

post-1275-0-20690800-1431267359_thumb.pn

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revolutionhope

im also thinking that the "actual fecundicity" value refers to the actual fecundicity of the individual ovigerous shrimp(s) not of the colony as a whole.

 

see this table -

 

:Fig 2. Relationship between actual fecundity and female weight (A) and between juvenile initial cephalothorax length and actual fecundity (B).

post-1275-0-43478300-1431267717_thumb.pn

post-1275-0-43478300-1431267717_thumb.pn

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revolutionhope

the whole thing is very confusing for me - but i did find this -

 

"Actual fecundity: the total number of hatched juveniles/female. This variable was calculated only for the Incubation period of Exp. 1."

 

and this -

 

"Interestingly, the GI of shrimps at 28°C was found to decrease from day 30 onward. It is well known that ovarian maturation and somatic growth are antagonistic processes from an energetic point of view. The energy costs of ovarian maturation are high due to the increase in biosynthetic work, which supports the lecithotrophic strategy of the embryos [38]. On this basis, a possible explanation for the decrease in GI may be that females maintained at 28°C allocated a greater amount of energy towards reproduction than towards growth compared to females at 24 and 32°C, as evidenced by the highest proportion of growth-phase ovigerous females being obtained at 28°C."

 

if you could humour me and check again for me ben i would really appreciate it!

 

love n peace

 

will

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revolutionhope

The way to work out which temp is best for getting shrimp to breed is to have a bunch of females with saddles, place them in (for example) 24 or 28*C, and then see how many mate and get berried. Of course controlling for how many shrimp get berried as a result of being moved from a different temperature would be difficult. Any breeding could be a result of a change in temperature rather than being at a specifc temperature.

All the anecdotal evidence indicates that higher temps (or a change in temp) stimulates breeding. The reason why I believe the aforementioned study does not provide proof about which temperature is best for stimulating breeding is because the authors were asking a different question - at what temperature do the shrimp grow fastest?

 

ovigerous means "carrying eggs" - if the shrimp already have saddles (eggs) then you can't calculate the proportion of females that are ovigerous?

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revolutionhope

I have to correct myself here. they identified females by havibf ovaries (saddles) ovigerous ones must therefore be those that arw carrying fertilised eggs..

but shouldn't the proportion of ovigerous females still be the same at each of the temps though considering that the results showed that the life cycle was completed within the 90day period at all 3 temperatures and that the body weight of shrimps were the same by that point as well?

I guess even if the reason for the OF difference is the faster growth and given that the actual fecundity is the same ... at the very least this proves that a whole new generation of shrimp can be raised faster at 28 than at 24 or 32 degrees doesn't it?

cheers im going to stop boggling myself now and hope for some more advice/explanation from someone such as yourself with experience understanding things like this!!

ps I found another experiment performed by the same laboratory that looks at culturing cherry shrimp with different surfaces for biofilm but I havent been able to access it since I dont have a university email address anymore.

its accessible via the researchgate website if anyone is interested :-)

love n peace

will

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mst_mugen

WOW! This thread is definitely getting very scientific! Haha But nevertheless, some very interesting discussions going on.

 

I would like to just quickly clarify something: When you guys say you notice a decrease in berried females during winter, besides obvious seasonal effects, was it on account of the following:

 

A) Females are just not developing saddles or developing saddles at a much slower rate?

B) Females are not molting as frequently?

C) When saddled females have molted, they are perhaps not giving off  as much pheromones and hence the males in the tank don't go on a crazy search and end up missing the "window of opportunity"?

D) All of the above?

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fishmosy

I have to correct myself here. they identified females by havibf ovaries (saddles) ovigerous ones must therefore be those that arw carrying fertilised eggs..

but shouldn't the proportion of ovigerous females still be the same at each of the temps though considering that the results showed that the life cycle was completed within the 90day period at all 3 temperatures and that the body weight of shrimps were the same by that point as well?

I guess even if the reason for the OF difference is the faster growth and given that the actual fecundity is the same ... at the very least this proves that a whole new generation of shrimp can be raised faster at 28 than at 24 or 32 degrees doesn't it?

cheers im going to stop boggling myself now and hope for some more advice/explanation from someone such as yourself with experience understanding things like this!!

ps I found another experiment performed by the same laboratory that looks at culturing cherry shrimp with different surfaces for biofilm but I havent been able to access it since I dont have a university email address anymore.

its accessible via the researchgate website if anyone is interested :-)

love n peace

will

I'm on Researchgate so PM me the link and I'll pass on a copy.

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fishmosy

hmm im still nto convinced - it does state

"At days 30 and 60 of the Growth period of both experiments body weight was lowest, highest and intermediate (P < 0.05) in juveniles maintained at 24, 28 and 32°C, respectively. However, at day 90 this variable was similar (P > 0.05) among treatments (Fig. 3). The growth increment (GI) was significantly lower (P < 0.05) at 24°C than at the other temperatures tested over the first 30 days. This was completely reversed during the following 60 days, with the GI of shrimps at 24°C exceeding that of shrimps at 28 and 32°C (P < 0.05). At the end of the Growth period, GI was lowest, intermediate and highest (P < 0.05) at 28, 32 and 24°C, respectively (Fig. 4)."

doesn't this mean that over 90 days they all grew at the same rate over the 90 days, just that during the first 30 days the shrimplets grew faster at higher temperatures?

Yes correct. After 90 days there was no difference in size. if you look at the stats, there is alot of overlap between treatments at 30 and 60 days suggesting they weren't really different at these times either, just enough for the stats to find a difference between 2 of the 3 treatments. (see how the treatments at day 30 and 60 are labelled as "a" "ab" and "b" respectively - lines with the same letters are not significantly different, that is the shrimp in those treatments were the same size). If you think about it logically, if X is equal to Y and Y is equal to Z, then X must be equal to Z. Edited by fishmosy

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fishmosy

the whole thing is very confusing for me - but i did find this -

 

"Actual fecundity: the total number of hatched juveniles/female. This variable was calculated only for the Incubation period of Exp. 1."

 

and this -

 

"Interestingly, the GI of shrimps at 28°C was found to decrease from day 30 onward. It is well known that ovarian maturation and somatic growth are antagonistic processes from an energetic point of view. The energy costs of ovarian maturation are high due to the increase in biosynthetic work, which supports the lecithotrophic strategy of the embryos [38]. On this basis, a possible explanation for the decrease in GI may be that females maintained at 28°C allocated a greater amount of energy towards reproduction than towards growth compared to females at 24 and 32°C, as evidenced by the highest proportion of growth-phase ovigerous females being obtained at 28°C."

 

if you could humour me and check again for me ben i would really appreciate it!

 

love n peace

 

will

Hey Will, what are you finding the most confusing?

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revolutionhope

I did get my head around it in the end :-) somr of the statements in the article were seemingly cintradictory - my biggest issue was my own misdefinition of the word "ovarian" :-) I thought saddled and berried classified as ovarian and not only berried!

Thanks mate :-) will find research gate link n shoot it thru to u. omw to a job atm

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