"Black spot" in roach.

[Vagabond]

Just by chance noticed a question on black spots in koi on the fishkeepers' forum.

 

It suddenly dawned on me that it is a long time since I caught a roach with "black spot" disease. During the 40s,50s,60s and 70s "black spot" was extremely common in the rivers Medway, Eastern Rother and Sussex Ouse - and in local ponds.

 

I don't know exactly when it seemed to disappear, but certainly I can't remember catching roach with "black spot" in the last ten years, and I've had several hundred in that time (but alas, am still awaiting that elusive two-pounder)

 

Comments anyone?

 

Anyone catching fish with "black spot" nowadays?

 

For information - "Black spot" is caused by cysts formed as a result of a parasite Neodiplostmum cuticola - the cysts become surrounded by black pigmented cells, giving a black spot which can be as big as a lentil. Several spots may occur on each fish.

 

The life cycle of the parasite involves water snails, then fish, and finally fish-eating birds.

[DenisO]

Every Roach over 1/4 lb I have caught on the Beult since the late 60's to date has had Black Spot. It doesn't seem to cause the fish any harm or distress.

I seem to remember, in the mists of time, this subject being discussed at club AGM's etc but I don't remember any specific outcome beyond it not being a major problem.

[Chris Plumb]

The last 2 or 3 seasons I caugght plenty of chub in the Kennet above Newbury with black spot - a few roach too - didn't have nearly as many with the condition this season. Thanks for the explanation Vagabond. I've oft wondered what caused it - the fish didn't appear ro be suffering because of it...

 

 

Chris

[Peter Waller]

Go with Vagabond on this one. At one time the beautiful blues & reds of a prime roach, with blackspot, were common up my way. To be honest, I hadn't noticed they had gone, until Vagabond mentioned it! Certainlt can't put a year on it.

[Cranfield]

The roach in the River Tiese in Kent have had black spot since I can remember.

 

They are in perfect condition and grow to specimen size, so it can,t be doing them any harm.

Its strange that Mother Nature hasn,t overcome this parasite, after all this time.

Get it sorted, Mother.

[singy]

I fish a lake where the roach and rudd are covered in it. Does them no harm whatsoever. They get well over 2lb, just looks unsightly.

 

Correct me if I'm wrong, but blackspot is the juvenile form of the swan mussel or a parasite associated with it, and I presume the lack of black spot these days is more to do with the decline of the mussel.

 

As part of their life cycle Swan Mussels produce, in spring, a parasitic larvae known as Glochidia, which attach themselves to fish. Glochidia are, in fact, baby Mussels. After an attachment is made a cyst is formed that feeds off the body mucus of the host fish. To be honest they do very little harm (do you know different?) and, usually, drop off within a few weeks going on to develop into adult Mussels.

 

[ 11. April 2003, 11:29 AM: Message edited by: singy ]

[Vagabond]

SINGY .....Yes I know mussel glochidia become encysted under the skin of fish, but does the cyst turn black??

 

The beast I am talking about (Neodiplostomum cuticola) is a trematode worm, eggs of which hatch in water, and the parasite emerges, enters the body of a watersnail, develops there to a freeswimming cercaria, and leaves the snail for the skin of the fish.

 

It then grows within a cyst, and the surrounding cells turn black. When the fish is eaten by a bird, the worms become adult in the birds gut, and eggs are shed with the birds faeces into the water.

 

I got this info many years ago from "Diseases of Fishes" by Van Duijn. Have believed it - until your post raises a doubt !!

 

It could be that we are both right here, and there is more than one cause of black spot - if Bruno reads this, comment would be welcome.

 

Like others, I have no evidence that fish come to any lasting harm due to a moderate infestation of black spot.

 

Interesting that black spot is still found in the Teise and Beult. I fish the Medway well above the entry of those two rivers, and as I say, I've seen no black spot in recent years on the Upper Medway (Now I've said that,no doubt Murphy and his laws will decree a bumper crop of black spots there next season!!)

[Bruno Broughton]

Black spot disease is an ailment in its own right, and those who have posted inforrmation about it are (errhum) 'spot on'.

 

Larval swan mussels do indeed attach to and live on fish, but this is a separate phenomenon. I guess that the larvae probably clip-on to the fins, and I've certainly seen little 'blebs' which could have been such. They, too, seem to cause no lasting harm to the fish.

 

[ 11. April 2003, 11:34 PM: Message edited by: Bruno Broughton ]

[RED HILLBILLY]

Way back in the 60s, fish in the Trent (mainly roach) were infested with a disease called UDN (ulcerative dermal necrosis). This was very nasty and the fish looked like they had a piece chewed out of them. The disease seemed to have died out after a few years. I have not fished in England for many years and wonder if this disease has ever come back. Recent posts have discussed fish being caught with bites out of them and posters have suggested otters or mink are responsible. Is UDM back? Bruno?

[monkeyboy]

Your right abouth the nematode worms. Dont the snails get horrible worm like growths making birds eat them.