[Zbrafish] Re: Question on Swimming Behavior

Lawrence, Christian via zbrafish%40net.bio.net (by Christian.Lawrence from childrens.harvard.edu)
Wed Sep 22 14:21:50 EST 2010


I would watch them closely, just to see if the behavior is persistent (from
lights on to lights off), or only occurs for a few hours after feeding.

It is not uncommon for some fish, especially certain strains, to display
this behavior after feeding. I believe (but can't say for sure) that it has
to do with then feeding on large amounts of certain types of processed feeds
and packing their guts to the extent that it compresses the gas bladder and
restricts air flow through pneumatic duct.  This interferes with their
ability to maintain position in water column.  As the food bolus is moved
along and through the DT they eventually are able to resume normal
positioning.   

Many years ago I noticed this, and like you worried that it was the clinical
presentation of some disease, until I noticed that it only occurred after
feeding.  The gut packing/pneumatic gut restriction makes sense, and we
never saw problems associated with this, so I don't believe it was/is a
disease, at least in our case.  Hopefully it is the same for yours.

P.S. You might want to try backing off the tetramin (or stop using it
altogether, but that's another subject for another time) and see what
happens.



On 9/22/10 9:31 AM, "Rachel" <pryor.rld from gmail.com> wrote:

> On Sep 21, 1:18 pm, Steven Waldron <waldr... from u.washington.edu> wrote:
>> Hi Rachel,
>> 
>> Sounds like a swim bladder issue.  Could be an infection or a defect.  
>> Is it a transient behavior? Do they show this behavior after eating the
>> tetramin?
>> 
>> Seems like your pH is a bit on the high side.  Though perhaps unrelated
>> to your issue, I would drop the pH down to around neutral or slightly
>> below (i.e. 6.8).
>> 
>> best regards,
>> Steve Waldron
>> University of Washington
>> 
>> 
>> 
>> Rachel wrote:
>>> Hi all,
>> 
>>> I've been culturing D. rerio for the last 4 months in 120L glass
>>> aquaria on flow-thru water exchange system.
>> 
>>> Lately, I have noticed that some of my fish (mostly gravid females)
>>> have been swimming with their body in an odd position, nose-down-
>>> caudal-fin-up ( similar to a '/' position). In addition, the swim
>>> pattern is not a fluid motion but more of a quick jolting forward
>>> movement. I have noticed this behavior in adult fish only >90 dpf.
>> 
>>> WQ: Temp 26-27 degrees, pH 7.96-8.05, D.O. 96% saturation
>>> Feeding regime: 24hr artemia a.m. and p.m.; Tetratmin Flake Food at
>>> noon.
>>> Stocking density: <5/L
>> 
>>> Any thoughts on what could cause this behavior and what it could mean
>>> for my population?
>> 
>>> I appreciate your time,
>> 
>>> Rachel Pryor
>>> Student Services Contractor, USEPA
>>> pryor.rac... from epa.gov
>>> 850-934-9279
>> 
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>> - Show quoted text -
> 
> 
> Thanks for your input Steve.  I don't believe this is a transient
> behavior.  I have begun researching D. rerio and swim bladder issues,
> so far have come up with inconclusive information.  I'll keep looking.
> 
> Again, thanks for your reply.
> 
> -Rachel
> 
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