Freshwater parasites

All,

After making great ceviche with LMB from Loch Lomond a debate was entered into about freshwater parasites.  I, having never seen a worm in the flesh of a freshwater fish, was fairly cavalier about the subject and boldly claimed that in our local drinking water lakes we would not need to worry.

Well, it is now time for me to eat a big plate of crow.

I was cleaning the crappie and bluegill that I caught from Lexington and nothing untoward was happening with the crappie, but when I filleted the bluegill I noticed something weird in the first fillet.

It looked like a little cyst or round ball of something.  It was small but not too small.  About the size of a head of a pin but round and white in color.  Thinking that it was a scar or something from my cutting board or whaterver I used my fingernails to pinch it out of the flesh.  There was a very minor "popping" feel, and onto my fingernail landed small squirming white thing.  It looked exactly like a tapeworm segment.  It was without doubt some sort of parasite.  Blech.  I found a similar cyst thingy in the other fillet, and suitably grossed out (and realizing one small bluegill was not really going to contribute to my tacos) I tossed the whole thing.

I now stand corrected about local lakes and parasites.

A couple of notes about it though:  The parasite was VERY easy to see, and I am certain that I would eat ceviche again, I just will be a bit more careful inspecting the meat. 

Note to self: Be less cavalier.

Note to Polepole: You were right man, it is something to think about.

Now, for the local fisheries biologists....Any idea what the parasite was or most likely could be?

MolBasser

After some searching, I suspect that I have identified the parasite.

I believe it is the yellow grub, Clinostomum complanatum.

I feel that this is right given the size and location (intra muscular) of the worm.

I am now looking to see if they are prevelant in california.

MolBasser

More info:

Yellow Grub, Clinostomum complanatum
Adult yellow grubs are flukes and live in a heron?s mouth. The larval stage, called a metacercaria, is the form referred to as a yellow grub. It appears as a yellowish cyst in the flesh or just under the skin of fish, most commonly yellow perch but also black bass and sunfish. Yellow grub doesn?t infect humans.

Life Cycle: 1 The eggs move from an infected heron?s mouth into the water while the heron is catching fish. Once in the water, the eggs hatch almost immediately into miracidia.

2 When the miracidia come into contact with a ram?s horn snail, they burrow into it and migrate to the snail?s digestive gland or liver. The miracidia develop into sporocysts, which produce larvae called mother rediae. Each mother redia produces three to 15 daughter rediae.

3 Daughter rediae form cercariae, which escape from the snail into the surrounding water. When the cercariae encounter a fish, they burrow into it and form a cyst, often near the tail or front fins. They develop into metacercariae —yellow grubs—within about 20 weeks.

4 When a heron eats infected fish, the metacercariae migrate to its mouth and matures into flukes. There the flukes produce eggs, beginning the cycle again.

Effects on Fish: Yellow grubs usually have no significant effect on fish.

Effects on People: Like other parasites of birds, this fluke will not infect people. If you want, you can remove the cyst with a knife. When the fish is cooked thoroughly, the cysts will die and not be noticeable.

MolBasser

What's the problem Chris?  "It is just a little extra protine."  The 2-inch worms I found in my Olive RF a few weeks ago were too much for me to eat that fish protine or not.

I personally wouldn't care that much in retrospect, but I was feeding it to my wife as well.

She would not approve.

Indeed, after reading it is no big deal if it was indeed the parasite I think it was.  Thankfully I am not a heron.

MolBasser

The wife factor was only part of my excuse.  They simply grossed me out.

Yeah......I think what got me was the wife first and the similarity to the tapeworm segments I have had to pick out of my cats butt in days gone by before I understood flea control.....

Blech!

MolBasser

A couple of notes about it though:  The parasite was VERY easy to see, and I am certain that I would eat ceviche again, I just will be a bit more careful inspecting the meat.

Mol, you also have to remember that not all parasites are full-grown.  There may be thousands of baby parasites in your ceviche that are too small to be obvious.

Bon appetit!   

Maybe, but the odds are that there are some developed ones.

Same deal with saltwater ceviche.

It is just a thing that people who eat raw fish gamble with.

MolBasser

Maybe, but the odds are that there are some developed ones.

Same deal with saltwater ceviche.

It is just a thing that people who eat raw fish gamble with.

MolBasser

I meant, some people cut around sections of a fillet with visible worms & eat the rest thinking it's worm-free.  False sense of security.