[Zbrafish] Re: Coleps

Bill Trevarrow via zbrafish%40net.bio.net (by trevarrow from EugeneResearchAquatics.com)
Wed Feb 11 21:19:41 EST 2009

Hi Tess,

I would add the following to the advice April provided:

There are two common sources of Coleps predating upon fish eggs:
1) the water system or aquarium water the fish laying the eggs come from
2) the cultures of food organisms used to feed the baby fish (often  
Introducing Coleps from either of these sources into your larval  
culturing system makes it possible for the Coleps to rapidly bloom if  
they are able to feed on an egg.

If one of these is contaminated, it is pretty easy for the other to  
get contaminated with Coleps. Once your water system is contaminated,  
it will be very difficult to remove the Coleps from the water system  
without nuking the whole thing with bleach. Paramecium cultures can be  
restarted relatively easily.

Normally, Coleps are saprophages, eating detritus. I guess fish eggs  
are just too enticing an object for them to pass up on. A dirty rather  
than a clean water system would therefore be expected to provide a  
better home for Coleps. This also provides another argument against  

Most commercially available cultures of ciliates are full of a variety  
of contaminants which should be removed such as:
Coleps, Didinium (a predator on paramecia), and other fast growing  
organisms that (under some culture conditions) can out compete  
paramecia. The stock center however is a source of Coleps free  
paramecia cultures.

Coleps and other unwanted organisms can be kept out of both sources by  
good quarantine procedures.
This also means that introducing new feed organisms (such as new  
paramecium cultures) into your facility can also introduce Coleps.  
Since they can be seen in a dissecting microscope, it is possible to  
produce a Coleps free culture.

A simple approach is:
1) dilute your initial culture
2) pick out individual organisms and put them into a new dish of  
culture media (diluting anything that came with them)
3) then pick out individuals again and put them into a new dish of  
culture media.

You can start a culture with a single paramecium. Using more results  
in a large culture sooner, but is more work and is more likely to by  
chance include a contaminant.

This process can be repeated several times, but two or three are  
usually sufficient to ensure the Coleps are not included. The more  
animals you transfer, the more work will be required, the greater  
possibility of a contaminant getting through, but also the more  
animals you have to start a new culture. I usually start two cultures  
in this way for a greater possibility of success.

I also have written up another approach has been described in an old  
issue of the Zebrafish Monitor which may be available on the ZFIN.org  

Some claim a salt concentration shock can kill Coleps. Others say it  
is just a temporary effect that does not kill them all and that  
eventually they come back. The sudden salt change could also stress  
your fish.

On Feb 10, 2009, at 12:15 PM, April wrote:

> Hi Tess,
> Here is my recommendation for containing Coleps and/or any other  
> unwanted organisms.
> 1.  Bleach all of your eggs as soon as possible.  If needed, you can  
> reference the egg bleaching protocol found in The Zebrafish Book, http://zfin.org/zf_info/zfbook/chapt3/3.2.html 
>  or on our website, http://zebrafish.org/zirc/documents/protocols.php#Egg%20Bleaching 
> .
> 2.  Be sure to remove ALL dead/damaged eggs before bleaching.
> 3.  After bleaching, keep your embryos in embryo media until they  
> have inflated their swim bladders and are swimming.  Zebrafish  
> larvae are the most susceptible when they have hnatched, but not yet  
> inflated their swim bladders.  Once the larvae are able to swim  
> properly, they can fend off most organisms.
> If you haven't already positively identified the organisms and would  
> like to, I recommend putting a few of these critters on a slide and  
> look at them under a compound microscope.  Coleps are quite small  
> and move in an intense twirling motion.  They have plates that cover  
> their exterior and make them look like hand grenades.  As you  
> mentioned, they are voracious and can consume an entire embryo in 45  
> minutes.
> For future reference, I recommend obtaining a good protozoa picture  
> book/guide.  We have 2 older books that are quite helpful, however  
> you might be able to find some newer better books with even better  
> pictures and information.
> - Patterson, D.J. (1996).  Free-Living Freshwater Protozoa (A Colour  
> Guide).  John Wiley & Sons Inc., New York, New York.
> - Berk, S. G.; Gunderson, J. H (1993). Wastewater Organisms (A Color  
> Atlas).  CRC Press LLC.
> If you continue to have problems, please let me know.
> Very best,
> April
> On Feb 9, 2009, at 4:17 PM, Fresquez, Theresa, DCA wrote:
>> Hello,
>> Does anyone know how to get rid of coleps? They are eating my  
>> zebrafish babies.
>> Thanks,
>> Tess
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> April R. Freeman (Mazanec)
> ZIRC Manager
> Zebrafish Int.'l Resource Center
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Bill Trevarrow, Ph.D.
Eugene Research Aquatics, LLC
trevarrow from EugeneResearchAquatics.com
Tel: (541) 844-9054
Fax: (541) 683-0996

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