Question
I used to get tiny "worms" on the back of a Buddha statue that was under the flow of an urn continually.  I think they are nematodes as they are very tiny, brownish black, and continually moving in an S shape.  This year we have had a lot of blanket weed in the pond and have had to clean the pump filter a lot.  Last time was about 3 weeks ago.  Yesterday we cleaned it again and it was absolutely stuffed full of these nematodes - thousands of them (with a very little blanketweed).  We took them out.  Are they dangerous to the fish?  Our water is now a lot clearer, even though the blanketweed is still growing slowly.  I did put lots of pond lilies in which might have helped the water balance. (There were plants in there already). We did have one fish that had a swollen, mould like growth 2 months ago and we euthanised. We haven't got the pond skimmers this year yet but the goldfish and koi seem to be doing well.   Concerned about the number of nematodes. Please help.

Answer
Dear denise,

Thank you for your question.
It is hard to get A correct ID of those worms just from text. However I think you are right.
And with that, there is no actual danger to it.
Some will even be "food" for the fish.
Also, waterlilies are not the best plants to reduce the nitrates from the water however they will do the job when they are combined with other plants like you told us.
So I think it is time to enjoy the pond!

Happy pondkeeping!
Kind regards,
Raf