diseased fish [Archive] - Fly Fishing Forum

: diseased fish

04-26-2002, 02:02 AM
I saw a massive fish working its way down the river bank today. Half its body was out of the water as it moved down river, and it had big white patches on its black back. I had no idea what kind of fish it was. I thought it might be some kind of carp. I tried to cast my fly to it, but it was quickly out of range. About an hour later, I saw the fish behind me on the other side of the river about 20 feet away in shallow water about 5 inches deep, so I spun around and cast my fly to him. I adjusted the position of my fly in the current so that it passed right over his nose, but he had no interest.

After about 10 casts, I heard a splash back on the other side of the river, so I turned and attempted to perform a pickup/forward cast from where my fly lay in the water. As I started forward, I felt a huge weight on my line. It was the monster, and he had taken my fly, or so I thought. He didn't fight at all but just made slow swimming motions, and I dragged him over to me like a log. When he got along side me, I could see that my fly had hooked the base of his dorsal fin. He was a huge, fat rainbow trout, and the big white spots on his black back were swollen blisters. If he had been healthy, I would have be waterskiing down the river as he made his runs, and I doubt my 6x tippet could have landed him. I unhooked him without touching him and he stayed about 3 feet from me slowly moving side to side in the slow current I was standing in.

Does anyone know what kind of disease that trout had?

Earlier, I also caught what I thought was a small brown trout but when I was getting the hook out of his mouth, I noticed the tell tale red slashes of a cutthroat trout underneath his jaw.

John Desjardins
04-26-2002, 09:29 AM
Per chance did the fish look like this. http://fraa.org/fungblnk.jpg
If so the cause is improper handling by another fisherman.

04-26-2002, 09:51 AM
John, that looks like UDN (ulcerative dermal necrosis) which apears periodically in wild Salmonids back in the UK. Mis-handling and removal of protective scales/slime could leave a fish vulnerable to the infection.

I did some scouting around and it seems that the underlying virus causing the disease has yet to be isolated. It seem most prevalent around spwaning time and fatalities are common at extended periods of high water temperatures.

Guidelines on various waters tend to vary as to what an angler should do when finding a fish in the condition newbie describes. Informing DEP would be a logical first step but should the fish be taken for examination?

John Desjardins
04-26-2002, 10:31 AM
I should have looked at the site I got that picture from before posting, and linked to this one insteadthis one instead (http://fraa.org/fungfish.htm).

Adrian, I hadn't heard of UDN. I'll have to look into it.

04-26-2002, 12:29 PM

That's it. What a shame! That rainbow was a beautiful fish with a black back and incredible rainbow coloring on its sides. Should I report that fish to some local authority?

04-26-2002, 03:18 PM

04-26-2002, 04:48 PM

Actually we get quite alot of that here in Arkansas. the common thought is that it is strictly due to mishandleing by fishermen. While I am certian that fishing pressure, water temperture, and a weakend fish due to spawning behavior are all part of our particular problem, I do not think that it is strictly due to fishermen. We have areas that are totally closed to fishing for months out of the year and fish in those areas still get this fungus. Another problem we have is Humped back fish. As well as fish that have a dark fraction of their body (ie head/tail or left/right). Most think that they are caused my brain damage from hooking or electro shocking of fish.

I would think that if your fish can survive from predation that she will be just fine. Once they can get their strength back they usually come back fine. We dodnt have that muc of a problem with our rainbows though so I'm guessing here.


04-26-2002, 04:50 PM
Holy smokes...spell check!!!