[Zbrafish] Embryo parisites, coleps, "twirlies"

April via zbrafish%40net.bio.net (by april from zebrafish.org)
Fri Feb 1 18:49:39 EST 2008

Hi Gabe,
It has been 10 years since I fought my battle against Coleps, and it  
was a tough battle to overcome.  Here are my suggestions:

1.  Bleach all of your eggs around 24 hours (approx. 35ppm bleach -  
Zebrafish Book concentration).
2.  Be sure to remove ALL dead/damaged eggs before bleaching (Coleps  
can hide and make their way through bleach in damaged eggs).
3.  After bleaching, keep your eggs/embryos in embryo media until  
they have inflated their swim bladders and are swimming.  Zebrafish  
larvae are the most susceptible when they have hatched, but not yet  
inflated their swim bladders.  Once the larvae are able to swim  
properly, they can fend off the Coleps.

Colpes are very hard to get rid of.  I am unaware of any drugs that  
will kill them, but I am fairly sure that UV works.  Bleaching and  
filtering our nursery water through a micron mesh helped us contain  
the problem years ago.  When we built the Resource Center, we were  
lucky not to bring them with us.  I continue to keep my fingers  
crossed that it stays that way.

Good luck, and let me know if you have any questions.


On Jan 31, 2008, at 5:47 PM, finchg from ohsu.edu wrote:

> ______________________________________________________________________ 
> __________
> I am looking for more information about coleps.  These are a small
> protazoa which parasatize larval zebrafish.  Under a dissecting scope
> they look like little transparent hyperactive beans, less than one
> hundredth the size of a zebrafish egg, comparable to a zfish blood
> cell in size.  I am only able to see them at >5X mag.
> -Here's a little mention in an old Zebrafish Science Monitor:
> http://zfin.org/zf_info/monitor/vol5.1/vol5.1.html#Coleps,%20Scourge 
> %20of%20the%20Baby%20Zebrafish
> Three seperate zebrafish labs at which I have worked have had minor
> problems with these little guys (Perhaps I am the vector, dunno).
> -Does anyone know more about these things than what is stated in the
> article linked above?  E.g. Life cycle, response to dessication, drugs
> with which to kill them?
> -Anyone had problems with them that they have overcome?  What
> strategies worked?  So far the only good strategy I know of is
> vigilant dish cleaning.
> -We have lately been having problems in dishes which we have bleached,
> which is perplexing.  Do other people see them surviving bleaching?
> Killed by bleaching?  (We follow the Volhard protocol)
> -Some folks have suggested raising water conductivity in our system.
> Anyone agree?
> -Also, does anyone know if UV can kill these or specifically what
> levels?
> -Anyone offering up advice or results regarding these pesky things
> will be my personal hero.
> Thanks, Gabe
> _______________________________________________
> Zbrafish mailing list
> Zbrafish from net.bio.net
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April R. Freeman (Mazanec)
ZIRC Manager
Zebrafish Int.'l Resource Center
5274 University of Oregon
Eugene, OR 97403-5274

Phone: (541) 346-6028 ext. 24
Fax: (541) 346-6151

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