Yes I am sure it is callamus worms.
Contact Pat (Mykiss) as soon as possible to treat. You are going to have to treat the whole tank. I would do a water change and vacume the gravel as good as you can to remove most of the worms that maybe in there. Good Luck
Treatment for the community tank is underway.
After the 2 hours of treatment, I can see those worms extruding from guppies' anus.
Yes, these worms tend to affect small fishes; guppies, endlers.
Cories and Rams seem OK.