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Fished tonight and caught a different Red Eye barbel.

Smaller fish and the other eye. Less pronounced than the first:


I've reported it on the Wandle Piscators site as they are in contact with the EA fisheries officer Tanya Houston.

The EA have replied back about the red eyed fish:

"It is not anything to worry about if it is restricted to a small
number of fish, and it is a native parasite that the lab would see very
regularly. It wouldn't fail health checks unless all fish were totally
infested and therefore not fit for purpose in a new water body. Feel
free to post this info if you want.

Diplostomum sp. are digenean parasites which are ubiquitous in the
aquatic environment and the metacercariae (larval flukes) are found
within the lens of several species of fish. Infection is dependent on
several factors including abundance of the snail host, water
temperature, flow rates and turbulence. It is also dependent on host
species as some species (in particular bream and roach) are more
susceptible to infection than others. Heavy infections of Diplostomum
can result in clouding of the lens and ocular pathology that could lead
to host blindness. This may alter feeding and general host behaviour.
Loss of sight will reduce feeding efficiency, which will impair
individual growth and may lead to emaciation and eventually death. Sight
impairment would also make individuals more susceptible to predation,
whereby heavily infected individuals may remain in surface waters,
making them more visible to potential prey species; in particular
piscivorous birds, which are the final hosts for Diplostomum sp..
Infections of Diplostomum sp. can have a serious impact on commercial
fisheries whereby suitable conditions and a high host density can lead
to increased transmission of the parasite between hosts.

Now back to the bleeding eye of the barbel. This is not going to be
caused by Diplostomum; this only causes clouding of the lens and
blindness. The bleeding in the eye is more likely to be due to the eye
being knocked, leading to rupturing of the capillaries. If this is the
case it will only cause problems for the individual fish and should not
be anything to worry about. It could be caused by water quality
problems, but if this was the case you would expect a large proportion
of fish to show similar symptoms (and other species too, not just
barbel), and this is unlikely."

Hi John,

It would be useful to keep a record on here of all the red-eye or blind fish that we catch on the Wandle. If it's more than a handful of fish then we should call in the EA.

Will