Success Story by Dr. Robert Durborow for fish disease diagnosis, an Extension outreach service provided by our Kentucky State University Fish Disease Diagnostic Laboratory (directed by Dr. Durborow and staffed by John Kelso, Extension and Research Assistant; Tifani Watson, Extension Associate; and graduate students Vincent Teye, from Ghana, and Adetola James Ogundipe, from Nigeria). This story highlights help provided to Jason Vajnar, Hatchery Manager, Kansas Department of Wildlife and Parks, in Meade, KS, who had bass infected with the protist parasite Costia (Ichthyobodo) and dying. Email correspondence is arranged from most recent back to the original email requesting help that was sent March 20, 2023:

From: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Sent: Tuesday, March 22, 2023 9:29 AM
To: Durborow, Robert <robert.durborow@kysu.edu>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>; Kelso, John <John.Kelso@kysu.edu>; Watson, Tifani <Tifani.Watson@kysu.edu>; Bussen, Nathan [KDWP] <Nathan.Bussen@KS.GOV>
Subject: Re: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

This morning the counts of living Costia was minimal compared to what we saw yesterday.  Amongst the entire slide today there were 3 moving cells.  Yesterday the count was easily a couple hundred.  We did not enumerate yesterdays numbers but, it is a HUGE difference compared to what we see today.  

My take is the treatment was effective.  It did cause one mortality to a fish that was infested quite heavily compared with the others.  

I will try to call you later this morning.  Thank you.

Jason D. Vajnar | Hatchery Manager

Kansas Department of Wildlife and Parks

12027 V Road | Meade, KS 67864

(620) 873-2701 | ksoutdoors.com

From: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Sent: Tuesday, March 21, 2023 9:29 AM
To: Durborow, Robert <robert.durborow@kysu.edu>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>; Kelso, John <John.Kelso@kysu.edu>; Watson, Tifani <Tifani.Watson@kysu.edu>; Bussen, Nathan [KDWP] <Nathan.Bussen@KS.GOV>
Subject: Re: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

Nathan and I obtained a sample and prepared the slide and saw under the microscope exactly what you described and what we see in your short video clip.  Only difference we may have a few more Costia in our slide mount as we took the sample from a heavily infested fish.   I just put the fish on a 2 ppm KMn04 bath.  I am so grateful for your response to this matter.  Thank you.

Jason D. Vajnar | Hatchery Manager

Kansas Department of Wildlife and Parks

12027 V Road | Meade, KS 67864

(620) 873-2701 | ksoutdoors.com

From: Durborow, Robert <robert.durborow@kysu.edu>
Sent: Monday, March 20, 2023 4:38 PM
To: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>; Kelso, John <John.Kelso@kysu.edu>; Watson, Tifani <Tifani.Watson@kysu.edu>; Bussen, Nathan [KDWP] <Nathan.Bussen@KS.GOV>
Subject: RE: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

 Sure, I know Nathan will do a good job….

Nate, you would simply put a drop of water on a microscope slide, scrape the suspected area on the fish with a cover slip and place it on top of the water drop.

You can get a rough focus using the 10x objective, but can better see the Ichthyobodo (Costia) with the 20x or 40x objective. They will be tear-drop shaped (red blood cell sized) and most likely flickering like a candle flame or swimming asymmetrically like a lopsided wheel. They can be treated with salt, KMnO4 or CuSO4.

From: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Sent: Monday, March 20, 2023 4:50 PM
To: Durborow, Robert <robert.durborow@kysu.edu>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>; Kelso, John <John.Kelso@kysu.edu>; Watson, Tifani <Tifani.Watson@kysu.edu>; Bussen, Nathan [KDWP] <Nathan.Bussen@KS.GOV>
Subject: Re: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

Dr. Durborow,

 Nathan Bussen our Biologist I, says he would be confident in preparing a wet mount slide.  What is he looking for and how does he go about preparing the slide?

 Thanks,

 Jason D. Vajnar | Hatchery Manager

Kansas Department of Wildlife and Parks

12027 V Road | Meade, KS 67864

(620) 873-2701 | ksoutdoors.com

From: Durborow, Robert <robert.durborow@kysu.edu>
Sent: Monday, March 20, 2023 1:26 PM
To: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>; Kelso, John <John.Kelso@kysu.edu>; Watson, Tifani <Tifani.Watson@kysu.edu>
Subject: FW: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

Jason,

Do you have a way to prepare a microscopic slide wet mount and look at it under a microscope?

If not, you might want to overnight an affected bass to us if it looks like it’s going to die anyway.

You mentioned Ichthyobodo as a possibility; it could be that. There’s also a possibility that it’s epitheliocystis.

It does not strike me as saprolegnia fungus.

Maybe John, my extension assistant, or Tifani, my extension associate, would like to weigh in on this.

Dr. Durborow

Robert M. Durborow, Ph.D., Professor

Interim Associate Research Director

College of Ag, Community, & the Sciences

School of Aquaculture & Aquatic Science

Kentucky State University

103 Athletic Road

Frankfort, KY 40601

Phone: (502) 597-6581

Mobile: (859) 684-8957

From: Vajnar, Jason [KDWP] <Jason.Vajnar@KS.GOV>
Sent: Monday, March 20, 2023 10:04 AM
To: Durborow, Robert <robert.durborow@kysu.edu>
Cc: Andrews, Aaron [KDWP] <Aaron.Andrews@KS.GOV>
Subject: largemouth bass broodfish - Icthyobodo or winter saprolegniasis?

Dr. Durborow:  

 This morning we pulled back our raceway netting to clean our raceways.  We noticed that our females have these white blotches between the head and the dorsal fin.  We see a picture similar to what we are seeing in the text book, Largemouth Bass Aquaculture.  My assistant manager and I are hoping you can confirm and provide a treatment scenario.  We have been intensively spawning largemouth bass in raceways since 2010 and have never seen this. 

I have also attached a photo of one of our males that has black splotches on it.  Any idea what this would be.  We do have a few males with one blotch or more. 

Thanks for any assistance you may provide.

Jason D. Vajnar | Hatchery Manager

Kansas Department of Wildlife and Parks

12027 V Road | Meade, KS 67864

(620) 873-2701 | ksoutdoors.com

https://gofile.me/6cBnf/BV4oGC9bH

Click on above link & choose “Open Hyperlink” to download the Ichthyobodo video. Then Open it to play (the figure below is a screen shot).

Screen shot of a video sent from Dr. Durborow’s files to help the Kansas hatchery identify the parasite.

Original photo of infected largemouth bass sent from Kansas Wildlife to Kentucky State University.

Note the white “film” on the anterior dorsal surface of the fish.