# Interesting fish...



## oldstinkyguy (Mar 28, 2010)

I caught a sunfish today ice fishing that was just covered in tiny black spots. In addition there were less numerous but larger yellow spots on the same fish. A little bit of research when I got home yielded some interesting information. The black spots that you can see, and feel if you rub your hand over them, are small cysts in the fish’s skin. According to my research what happens is that a fish-eating bird like an eagle, osprey, great blue heron, kingfisher, gull or cormorant consumes an infected fish and the black spots, which are, in fact, tiny encapsulated worms called trematodes, mature inside the bird’s digestive system.
Once they mature, the worms lay eggs which the bird passes into the water in its droppings. The eggs then hatch into microscopic organisms called miracidia that usually have only about 24 hours in which to swim around and find their next host that is typically a snail. Once the miracidia worm their way into the snail, the parasite develops into its next life form, emerging from the snail as a tiny creature called a cercariae, that swims around in the water looking for a fish in which to infect. When the parasite successfully burrows into the fish, the fish reacts by encrusting the little sob in a cyst with black pigmented melanin, which is the black spot that we can see and feel.
The black spot can survive in the fish’s flesh and skin, almost as though it is lying dormant, for many years, while it waits for the fish to be eaten by a bird, so that the process can repeat itself once again.
The larger yellow spots it turns out are also a closely related parasite that follows the same bizarre twisted cycle of bird eats fish, parasite multiplies in birds gut, gets pooped out, matures in a snail, then swims around looking for a fish to attach to and repeat the whole thing over again. 
Sometimes its amazing how weird nature can be, even in everyday places like the pond down the street.


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## Opiedog (Jan 7, 2009)

Interesting, thanks for sharing.


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## DHower08 (Nov 20, 2015)

The black spots are a type of parasite. They do not affect the meat or safety of eating the fish. When cooked it kills whatever that parasite is. Use to throw those ones back but not anymore. Keep em all the same


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## Southernsaug (May 23, 2019)

They are Neascus or black spot disease. It is a grub and you usually see them where herons hang out over the water. Herons are intermediate host. They are only a grub cyst in the skin mostly. Cook it and eat it your fine. Here's teh wiki:






Black spot disease (fish) - Wikipedia







en.wikipedia.org


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## Fish Whisperer (Jul 11, 2006)

Oldstinkyguy thanks for sharing. Your the best. I say it again, the Enquirer should publish outdoor articles by you.


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## Southernsaug (May 23, 2019)

The yellow spots are yellow bass grubs


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## Saugeye Tom (Oct 6, 2010)

oldstinkyguy said:


> I caught a sunfish today ice fishing that was just covered in tiny black spots. In addition there were less numerous but larger yellow spots on the same fish. A little bit of research when I got home yielded some interesting information. The black spots that you can see, and feel if you rub your hand over them, are small cysts in the fish’s skin. According to my research what happens is that a fish-eating bird like an eagle, osprey, great blue heron, kingfisher, gull or cormorant consumes an infected fish and the black spots, which are, in fact, tiny encapsulated worms called trematodes, mature inside the bird’s digestive system.
> Once they mature, the worms lay eggs which the bird passes into the water in its droppings. The eggs then hatch into microscopic organisms called miracidia that usually have only about 24 hours in which to swim around and find their next host that is typically a snail. Once the miracidia worm their way into the snail, the parasite develops into its next life form, emerging from the snail as a tiny creature called a cercariae, that swims around in the water looking for a fish in which to infect. When the parasite successfully burrows into the fish, the fish reacts by encrusting the little sob in a cyst with black pigmented melanin, which is the black spot that we can see and feel.
> The black spot can survive in the fish’s flesh and skin, almost as though it is lying dormant, for many years, while it waits for the fish to be eaten by a bird, so that the process can repeat itself once again.
> The larger yellow spots it turns out are also a closely related parasite that follows the same bizarre twisted cycle of bird eats fish, parasite multiplies in birds gut, gets pooped out, matures in a snail, then swims around looking for a fish to attach to and repeat the whole thing over again.
> ...


OSG where the hek have u been??????


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## kingofamberley (Jul 11, 2012)

Free extra protein!!! Thanks nature!


Sent from my iPad using Tapatalk


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## Saugeyefisher (Jul 19, 2010)

Saugeye Tom said:


> OSG where the hek have u been??????


I follow him on the gram...


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## Muddy (May 7, 2017)

Southernsaug said:


> The yellow spots are yellow bass grubs


Southernsaug-I caught a fat 10” bluegill out of one of my ponds last week that had the yellow grubs on the skin and tail fin. I’ve never seen them on the outside of a fish before, only in the flesh. It was nasty looking. I released the fish. Afterwards I wished I would have thrown in in the weeds. By leaving that fish in the pond am I putting other fish at risk of getting infected with these? Should any visibly infected fish in my ponds be removed to try and eradicate this as much as possible? Thanks for your expert input on fish biology.


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## Southernsaug (May 23, 2019)

muddy, No harm in throwing it back. Most likely the other fish are already infected. It's still a good practice to remove any unhealthy fish you see. The grubs are spread by birds so there's not much you can do. Chances are the exterior parasites may of been Ich, do you know what ich is?



https://aquaculture.ca.uky.edu/sites/aquaculture.ca.uky.edu/files/srac_476_ich_white_spot_disease.pdf








ich on fish diagnosis - Search


Find high-quality images, photos, and animated GIFS with Bing Images




www.bing.com





Treating your pond in the spring with copper sulfate will help. A lot of people like to put fish from the wild into their ponds. Before you do this look the fish over good for signs of disease. Any inflammation, sores or spots and don't do it.


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## Muddy (May 7, 2017)

Thanks for the info. It wasn’t ich. It looked exactly like the tan/yellow boogers that I’ve seen in many freshwater fish before, but usually in the flesh. They were almost topical or partially imbedded in the skin. We have herons around a lot, they might be the culprit. I’ve stocked Red Ears to control the snails. I was hoping that controlling snails would help control the parasites that rely on snails as part of there life cycle.


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## Muddy (May 7, 2017)

Look at the tail fin picture that the OP posted. You can see some tan/yellow parasites in the fin. That looks like what I saw. It was in the tail fin and base of the tail fin where I saw them concentrated on the bluegill that I caught.


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## Southernsaug (May 23, 2019)

Oh I have seen them on the exterior too, that and in the meat. The tail is a typical spot to see them, Cook and enjoy.


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## Muddy (May 7, 2017)

I’ve ate plenty of crappie with the black spots, but I draw the line at the yellow ones usually. I learned the trick years ago to hold the fillet up to a light and look through the meat to see if it has parasites. Ignorance is bliss I guess. Before I learned that trick I just ate the fish parasites and all. I know that they won’t hurt you when cooked properly, but it’s a psychological thing I guess. A lot of saltwater fish have parasites in the flesh as well when you look for them.


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