Hello:

I lost 3 Koi in my pond over the winter. Two were new from Petco and a large
one that was there when we bought the house last October. We've been
learning how to maintain the pond mostly through error. Right now we have
about 7 gold fish that seem really healthy. The filter works well and I'm
doing 25% water changes every two weeks now.

After the two small koi died I did an Ich treatment for 3 days that claimed
to remove almost all parasites. But it failed to save my large Koi.

I went to clean the filter today and I noticed a large number of small
worms. Deep red about 1/2" x 1/32". In other word "very small". I've seen
them before but it looks as though they are growing in number.

I live in Austin TX. Are these worms normal? Can they harm fish? I can
provide pictures if need be.

Thanks

Jim