Thank you, Robert That gives me a good Idea what to look for.
I have one female, which is kinda bloated but I do not think I have this worm. I will keep an eye on it. I just bought another female and three days after I bought her, she had 12 babies. So my whole tank is nuts again ... I wrote about it in "Frisky aggressive guppies"...
My fish can not sit still!!!

Elli