Questions - Need some input

So, here it goes…

As usual, after half an hour lights off, I feed my Anemone, for that i closed all circulation to let it feed. Almost half an hour later I observed where it reached. I saw almost 18” long blue color threadworm was floating in the tank. Immediately I caught it with the help of net and put it in measuring jug.
See Video:




While I was catching it, 2” part of it broken down in the ...