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What are these spots on a golden shiner?


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#1 Guest_dsaavedra_*

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Posted 08 January 2009 - 07:49 PM

most of the larger golden shiners from my creek have these little black spots on them. the spots are raised from the skin, and dont rub off. i haven't tried picking at them with a fingernail, but they dont come off just from rubbing a finger across them.

are they parasites or what? i sure hope not because some of the shiners i have in my aquarium have a few of these spots on them.

this was the most extreme case of the spots i have seen yet, and this is also the biggest shiner i have caught from down there:

Posted Image

same fish:

Posted Image

#2 Guest_ashtonmj_*

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Posted 08 January 2009 - 08:24 PM

It's a parasite caused by a trematode. It goes between birds and fish and the state you see shoes up as a black cyst.

#3 Guest_dsaavedra_*

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Posted 08 January 2009 - 08:31 PM

well that sucks!

is it bad for the fish? the fish with the parasite do not seem like their doing bad at all. they don't flash on rocks and decorations at all.

also, will it spread to other fish in the aquarium?

#4 Guest_ashtonmj_*

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Posted 08 January 2009 - 09:17 PM

I don't think they are harmful to the fish. Without being consumed by a bird the parasite cannot complete the life cycle and spread to other fish.

#5 Guest_CATfishTONY_*

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Posted 09 January 2009 - 05:14 AM

well that sucks!

is it bad for the fish? the fish with the parasite do not seem like their doing bad at all. they don't flash on rocks and decorations at all.

also, will it spread to other fish in the aquarium?


HI dsaavedra, Fish in my area have this as well. one of my shiners has maybe 100 black spots on it.
this is a link i found some time back when i was asking the the same ? you are.


Black spots

Black spot disease is commonly observed in rock bass and other sunfish, bass, pike, perch, minnows, and other fish species. It can be identified by the presence of small black spots, usually about the size of a pin head, in the skin, the fins, the musculature, and the mouth of the fish. The black spots are caused by pigment that the fish deposits around the larval stage of a parasitic digenetic trematode, usually a Neascus spp.

The lifecycle of the "black spot" parasite is complex. The adult parasite is found in a fish eating bird, the kingfisher. The larval parasite is transferred from the infected fish to the bird during the feeding process. In the kingfisher, the larval stage develops into an adult parasite. The adult parasite in the intestine of the bird produces eggs that are eventually deposited in the water. There the eggs mature, hatch, and develop into the miracidium stage of the parasite. The miracidium infects a snail. In the snail, the miracidium develops into the cercaria life stage. The cercaria leaves the snail and actively penetrates a host fish. In the fish, the parasite becomes encysted. In about 22 days, black spots form around the cyst. This entire lifecycle takes at least 112 days to complete.

In general, the presence of the "black spot" parasite does not affect the growth or the longevity of the infected fish; however massive infections in young fish may cause fish mortality. The parasite is incapable of infecting humans and, as is the case with all fish parasites, it is destroyed by thorough cooking. When fish are heavily infected, some anglers prefer to remove the skin to improve the appearance of the cooked fish.

For further information please reference:

* Parasites of North American Freshwater Fishes
by G. L. Hoffman (This book may be available from your local University Library)
* Click here for a University of Michigan web page on flat worms.

Numerous state Fisheries' agencies and other web sites describe parasites --- try typing "Neascus" or "Clinostomum" in search engines to learn more.

Like many biological phenomenon, prevalence of worms and parasites may be greater in some years and during some seasons for a variety of reasons, including an abundance of intermediate host mollusks and birds. Bluegills are a colonial spawner and congregations in early summer provide opportunity for infested fish to be in close proximity to one another.

#6 Guest_dsaavedra_*

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Posted 09 January 2009 - 11:32 PM

thanks for that article catfishtony. very helpful.

its good to know this won't hurt my fish.

so if i am interpreting all this correctly, the black spots will eventually die off because they are only a larval stage and they will be unable to complete the cycle?

#7 Guest_CATfishTONY_*

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Posted 10 January 2009 - 09:53 AM

thanks for that article catfishtony. very helpful.

its good to know this won't hurt my fish.

so if i am interpreting all this correctly, the black spots will eventually die off because they are only a larval stage and they will be unable to complete the cycle?

I have one fish that's four months old now(captive care) and it still has black spot.

#8 Guest_smilingfrog_*

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Posted 10 January 2009 - 11:21 PM

thanks for that article catfishtony. very helpful.

its good to know this won't hurt my fish.

so if i am interpreting all this correctly, the black spots will eventually die off because they are only a larval stage and they will be unable to complete the cycle?


That is correct. However, I don't know how long it will take for them to die off. I would guess that they can remain in the "black spot on a fish" stage for quite awhile, as they would have no control over when/if the fish they are on gets eaten. (ie. just because the parasite might be ready for the bird stage of it's life 22 days after infecting a fish, doesn't mean the fish is is going to get eaten on day 22. It pays for the parasite to be able to wait around awhile.) I would guess, and I stress guess, that they will die off in less than a year, as the black spot does seem to be seasonal in places. For example, Northern Pike in a Northern Minnesota lake I fish, have more black spot in late summer than in spring so it does seem to go away.
At any rate unless you add some infected snails to your tank or have a kingfisher doing his business into it, your fish will not get reinfected by any new black spot.

#9 Guest_sandtiger_*

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Posted 11 January 2009 - 09:38 AM

My pumpkinseed had blackspot when I first brought him home, I've had him for just over three years now and they're gone, I didn't noticed when they vanished but he doesn't have them. I recall reading that they can live for about four years on the fish.



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