Red Tumors ? (May 30, 2005)

[Jason Howell]

 Don't know my anatomy.I think it was the "air bladder" maybe. It was a white membrane anyway.
Litte red marks,in a circle. Multipe circles. Fillets look normal. She was also still full of eggs,they were almost hard and discolored.
Thanks,
Jason

[Fred Snyder, Ohio Sea Grant Extension]

 Hello Jason,

Yes, that was the walleye's air bladder that had all those red lesions, and they are caused by a bacterial infection. This is very common each spring - virtually every walleye has these lesions to some degree. The lesions appear to diminish through the summer as the fish regain health.

Infections like this are usually caused by common strains of bacteria that are always present. Walleye (and other species) get physically run down through their spawning season, and with lowered resistance, become prone to more severe infections. The lesions pose no threat to humans, so send those fillets into the fryer.

[Jason Howell]

 Fred,
Thank you!
Jason
P.S. This the best factual board around!

[CRAIG BETZ]

 Will this stress also cause red spots and tumors externally as well?I have read a few posts regarding concearn for this condition,infact we have pulled some fish exhibiting this condition ourselves along with color variations and I had related it to the same stress condition.It seems as though there are less of those fish in the last few weeks and the overall quality of appearance is improving as the spawn has passed for the best part,but I have noticed people east still talking about the condition,is that due to the colder waters and later spawn trigger?Thank you for being such a great group of people.

CRAIG

[Fred Snyder, Ohio Sea Grant Extension]

 Craig,

The red tumors on the skin you see in the spring is a virus called lymphocystis. It causes individual skin cells to swell to huge size, then they rupture, releasing more virus. As walleye spawn they get lots of abrasions on their skins, allowing the virus to enter and infect them, which is why you see it so much in the spring.

Think of lymphocystis as massive cold sores on the walleye. It looks bad, but eventually heals up. And no worry here - lymphocystis does not infect humans - strictly a fish disease. Skin the fillets and you'll never know it was there.

Later in the year a similar disease called dermal sarcoma sometimes appears.