Water temperature for breeding and raising RCS

[Dr Mike Oxgreen]

A while ago I was having problems with my blue Neocaridina shrimp dying, and somebody in a fish shop told me that my temperature of 25°C was right at the top end of their range. As a result, I lowered my temperature to 23°C. Having read this interesting scientific study, I now believe that advice was wrong.

The study looked at the incubation and subsequent development of hatchlings at 24°C, 28°C and 32°C. It found some interesting results. In no particular order:

• The incubation period is much longer at 24°C (21 days) than at 28°C (just 12 days).
• Growth rate of hatchlings at 24°C is slower for the first 30 days, but they then grow more quickly and actually catch up with their warmer colleagues such that after 90 days' growth they're the same size.
• Survival rate of hatchlings is better at 28°C than at 24°C.
• Hatchlings become sexually mature more quickly at 28°C than at 24°C, but at 32°C the young females fail to keep any eggs they produce.
• Contrary to what is sometimes written, the number of hatchlings produced by each female is not correlated with the size of the female.

Last night I spotted a number of hatchlings about 2-3mm in size, which explains why I hadn't spotted the berried female for a week or two: I figured she'd either died or hatched her eggs and become indistinguishable from the other shrimps, and it now appears the latter has happened - yay!

I'd really like to speed up my shrimps' reproduction, and in the light of the study it seems my lower temperature will be slowing down incubation significantly and may be reducing the survival rate of the babies. The study didn't address the effect of temperature on the fertility of adult females, but it's quite possible that a warmer temperature will bring females into breeding condition more frequently.

So I've decided I'm going to reverse my change of temperature and increase it initially to 24°C for a week, and if that seems okay I'll go up to 25°C. I won't go higher because it'll start affecting my plants.

For the avoidance of doubt, it's important to note that this applies to RCS (Neocaridina), but it does not apply to CRS (Caridina) which I believe do prefer rather cooler conditions.

 

[Dr Mike Oxgreen]

Slightly rubbish picture:

 

[Aqua Hero]

Yeah I noticed a similar thing. Before my temperatures were around 26c and I would see shrimp everywhere with a lot of pregnant females, but since I lowered the temp for better plant growth (21-23) their breeding rate is slower


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[mantis147]

Mine breed like mad at 22c, 140-160tds.

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[Dr Mike Oxgreen]

Mine breed like mad at 22c, 140-160tds.

Then they would have bred even faster at a higher temperature!

 

[sciencefiction]

I've kept mine at around 24-25C for the time I've kept shrimp which is roughly 4 years, not for any particular scientific reason. They breed like rabbits and I have never had problems with them keeping them at that temp. But I do have an unheated shrimp tank and they survive and breed in temperatures as low as 12C, really tough creatures. I don't think what the shop advised you is accurate.

 

[rebel]

I've never produced them profusely but they have survived temperatures from 6 to 32 in my case. That paper is interesting indeed.

 

[rebel]

I've read part if the paper and thought that the accuracy if temperature regulation to one degree was a little amateurish. I thought 0.1 degree would have been abetter choice. Thoughts?

 

[Dr Mike Oxgreen]

I've read part if the paper and thought that the accuracy if temperature regulation to one degree was a little amateurish. I thought 0.1 degree would have been abetter choice. Thoughts?

I don't think that undermines the usefulness of the results, when the experimental temperatures are 4°C apart.

Also, I suspect they're probably just quoting the accuracy of the equipment they used, as stated by the manufacturer of the heater. I would bet that most manufacturers would understate the accuracy of their heater; the actual accuracy of the temperature regulation was probably much tighter than 1°C.