[Zbrafish] Re: seasonal mortality?

Lawrence, Christian via zbrafish%40net.bio.net (by Christian.Lawrence from childrens.harvard.edu)
Wed Dec 10 21:35:53 EST 2008

I see the logic in seasonal changes in water supply, but I guess the reason why I tend to not be much of a believer in this affecting survival in controlled facilities is that these changes, if and when they occur, should be for the most part be detected by routine water quality testing.

However, I suppose at least one problematic parameter that would go undetected in most facilities (ours included) is chloramines/chlorines.  One could certainly imagine a scenario in which there is an increase in the use of such chemical treatments during the fall in certain regions, and if you're not testing for it (because you don't expect it to be there), AND your RO water service provider (if you have one) isn't checking for it, or isn't maintaining the RO system properly, then it could get through and be causing a problem.  In such circumstances, one could simply test for it to see if this might be the case and ensure that RO units be serviced regularly.

But changes in other parameters, like pH, alkalinity, salinity, etc. should be readily observable and therefore correctable.

The other issue is that aside from toxins or heavy metals, zebrafish - even larval and juvenile stages - are very tolerant of variable conditions. Or they should be, at least.  If they aren't, poor tolerance for challenges is likely indicative of an underlying problem more serious in nature.


On 12/10/08 6:16 PM, "Jocelyn" <jocelyn.mcauley from gmail.com> wrote:

Off list I received three emails indicating a shared experience of
increased nursery mortality in fall.

More about our parameters:
+ we have an RO/DI water source.
+ we have consistent personnel year round (ie full time staff, no
student workers).
+ we feed powdered AP diet and raise brine shrimp for our nursery fish
(no paramecia, rotifers, etc ).
+ another zebrafish facility in the same building reported anecdotally
about similar problems at the same time.

Will seasonal changes in city water persist through a RO/DI system?
I'm coming to think so?

thanks for your feedback.
As always, its been interesting.

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