An Unwelcome Visitor Revealed

March 19th, 2010 by Melissa Kipp

He may not have been expected, but we’ve taken him in and figured out his origins.  Who am I talking about?  A new parasite, found on one of the Science Museum’s new goldfish!  

This blogpost was originally going to feature images and information about our two new goldfish tanks, set up by Nursery Teacher and Animal Care Specialist, Natalie Schneider Cheung.  However, in her careful watch for the tanks to reach equilibrium, she discovered a green spot on one of the new goldfish.  The next day, the spot had moved… to another fish!!  Something was off, and we needed to find out the answers.  

Dr. John Loret, SMLI Executive Director and marine biologist, took a look at the problem and declared it a “Parasitic isopod.”  Further research by Christie Schlaner and David Miller clarified the critter’s background even more:  Argulus japonicus.   This species originates from China, but has spread to Europe, North America, Africa, and Australasia due to accidental introduction during ornamental fish trade.  It makes perfect sense that this little animal found his way onto one of our fish, since they can free-float in water for 3-5 days before finding a host.  

Brave Natalie and fellow teacher Jennifer Spina were able to remove the pest with tweezers, and it’s a good thing they did.  Eggs of this species are laid in batches of up to 200 and hatch 2-4 weeks after they are laid. We will keep our eyes open for new hatchlings.

Do you think our classification is correct?  Judge for yourself.  I’ve taken images with my Canon PowerShot, a little tricky on the television screen of our video microscope.  

The first image is to show actual size of the parasite.  (He’s just below the “cm” of the ruler, which is placed under a watery petri dish)

 

Actual size of parasite: 0.5 cm

Actual size of parasite: 0.5 cm

The next images were taken on the screen of the video microscope:

Under the video microscope... Argulus japonicus?

Under the video microscope... Argulus japonicus?

 

Another view of the up close and personal parasite

Another view of the up close and personal parasite

 

Compared to the University of California Museum of Paleontology’s classification, this looks like a pretty sure case of fish lice.   Either way, this guy is fascinating to watch.   If you’ve seen one before or have any input, let us know!  And stay tuned.. the fish tank post will be up in the next few weeks.

–Melissa Kipp

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