Perch disease ?

[Andy_1984]

my local canal has been prety good for lots of perch but ive been pulling out alot with what appears to be some sort of disease.

 

its a large circle on the side of its body about the size of a 20p peice which is red with a white spot in the middle of it.

 

i have only noticed them on the perch but one roach did have what seemed to be little tiny versions of it on its belly about 6 little ones

[Steve Burke]

These could be ulcers caused by aeromonas bacteria, although it's difficult to say without seeing them. These infections aren't uncommon with perch, especially when they're under stress such as in high water temperatures, immediately after spawning or when the perch population is very high. Often the perch survive the infection, but from time to time the fish are so stressed that the infection is fatal.

 

Aeromonas infections have in the past wiped out almost entire populations of perch. For many years it was thought that these infections were indeed the dreaded "perch disease".

 

However more detailed research showed that the perch were being killed by a variety of different diseases. The suggestion was that something was weakening them. This was as far as we could go when writing "The Book of the Perch". However, some new research being done at the time was coming up with the probable answer, and we agreed not to publish it as the scientists weren't quite ready to go public.

 

The common factor seems to be an infestation by a tiny parasitic nematode worm. The parasite weakens the perch to such an extent that they fall victim to infections that they'd normally shake off. The parasite is spread by seabirds, and it's interesting that Forum member Jim Gibbinson had pointed out some years earlier that some waters that weren't visited by ducks had no perch disease whilst other nearby ones where ducks flew in were affected. You can see how close Jim was!

 

I'd add that "perch disease" (PD) is nothing new. In researching The Book of the Perch (that incidentally contains an excellent chapter on PD by virologist and ex-Perchfisher Drew Young), Peter Rogers tracked severe outbreaks of perch disease back to at least Victorian times.

Edited July 4, 2006 by Steve Burke

[Steve Walker]

and it's interesting that Forum member, Jim Gibbinson, had pointed out some years earlier that some waters that weren't visited by ducks had no perch disease whilst other nearby ones where ducks flew in were affected.

 

Hah! See, I told you all, ducks are evil!

[Steve Burke]

Steve, I think it's more the case that where ducks don't fly in seagulls don't either.

 

Unfortunately cormorants weren't implicated, but then we didn't have the cormorant problems that we do now.

[Steve Walker]

They're probably collaborating with the seagulls. They're not to be trusted I tell you! Nurse!

[Andy Macfarlane]

Try and get photographs Andy, E-mail them to me and I'll make sure they get to someone who can identify the problem.

[Andy_1984]

obviously this pic is not a perch but the dissease/blemish or what ever the hell it is is prety similar ive also pulled a few out like this like the last one with small red spots on its belly.

 

the picture isnt great so ill describe it a little aswel, the red marks look a little like some sorta small gooey pinkish tumor the scales around the area are all discolored. the perch spots are similar but bigger with a thin red outline around a large white spot that sticks out looking like the scales are being pushed outward and is nearer its gills on the side.

 

this roach is also prety big. it made me kinda upset to see a nice roach in this kinda condition

[ColinW]

That just looks like a jack's had a go at it.

[Andy Macfarlane]

I think I'd have to see one in the flesh Andy because that picture doesn't tell us much BUT from what I can see, I'd have to agree with Colin. It looks like the kind of damage suffered when a Pike has had a go.

[Andy_1984]

I think I'd have to see one in the flesh Andy because that picture doesn't tell us much BUT from what I can see, I'd have to agree with Colin. It looks like the kind of damage suffered when a Pike has had a go.

 

i was thinking that but there was not a single scratch or mark on the opposite side of it