6 replies to this topic

[UncleWillie]

Since February 2015, I have been leading a relatively large fisheries assessment on the Chattahoochee River (middle, lower), sampling twice a month for over a year until this past spring.  During this time, we've come across several different DELT (deformities, eroded fins, lesions, tumors) anomalies.  I've been able to identify most of the bacterial infections and parasites, but this one keeps throwing me for a loop.

 

We've only observed this black-colored anomaly in gizzard shad.  In early stages, this black anomaly starts small, usually has a soft, fuzzy texture, and is always located near the head or back of the fish.

Attached Files

•  P4020093.JPG   148.59KB   0 downloads

Edited by UncleWillie, 26 August 2016 - 11:55 AM.

[UncleWillie]

As the black “fuzz” grows, it hardens and become more bulbous.  Again, frequently, we observe this black anomaly near the head and back, but we’ve observed it in parts of the body as well.

 

Attached Files

•  P4020091.JPG   126.27KB   0 downloads
•  P4280054.JPG   183.81KB   0 downloads

Edited by UncleWillie, 26 August 2016 - 11:56 AM.

[UncleWillie]

Here is a severe case, with the black growth near head and dorsum.  However, in this case, you can also see a lighter-colored growth that is not quite as firm and has a bit more of a gelatin-like texture to it.

 

I’ve searched my resources and cannot confidently conclude what type of anomaly we are seeing.  I’ve only found one photo online is on TWRA’s website: http://www.twra.us/F...asites_TWRA.htm

 

The photo only this says is “tumors”.  Has anyone seen this or have any idea on what we are observing?  Any help would be much appreciated!

Attached Files

•  P4020088.JPG   175.42KB   0 downloads

Edited by UncleWillie, 26 August 2016 - 12:02 PM.

[gerald]

In gross appearance it reminds me of Lymphocystis (usually white on most fish) so maybe it's a similar virus ???

Have you cut any of these growths open to see what they look like inside?

[UncleWillie]

Thanks, Gerald. We did come across some presumed Lymphocystis in spotted suckers. In general, this just looked different. I did not cut any off to examine the internals. However, the "fuzzy" growth that you see in the caudal fin seemed to be able to break apart if you ran the back of a fingernail across it. The black nodules were much harder and were not able to scrape off. I reckon I should have done some dissecting!

Attached Files

•  PB110155.JPG   107.35KB   0 downloads

Edited by UncleWillie, 26 August 2016 - 02:42 PM.

[UncleWillie]

I have read through a fish disease/infection/parasite book a veterinarian friend gave me a while back, and then used some of that information to search for more literature online.  No definitive answer, but so far I am being led away from bacterial or viral infections, and more towards cancerous.  The best info so far points towards some sort of pigmented cancerous cells or tumors (e.g., melanoma).  I will update as I find more info.

[brackishdude]

I am a decades-long amateur fishkeeper on my own time, and a full time human oncologist to pay the bills. 

 

I'm not sure how hard you want to chase this down, but If you don't have a local fish-pathologist at UGA or the equivalent, I would consider contacting a local cancer center/hospital and ask for the pathologist.  Explain that you would like to bring in some fresh tissue for pathologic evaluation.  They are just regular folks who may well find the exercise a nice break in the routine, intellectually interesting, or just fun!  Don't be put off if the first one you try declines.

 

They can thinly slice the tissue and mount onto microscope slides, run special stains, and be able to give you the slides as well as images that you could email to any dedicated fish pathologist.

 

Good luck and keep us posted.