I recently started a fresh water tank. It's about 6 weeks old. I have a betta, cory and some ghost shrimp. After I feed tonight i saw a white thread like worm in the rocks.At first I thougt it was a cat hair,sense I have a whit cat.But when i removed the object it curled up very slowly.My question is what kind of worm is it? Where did it come from? Is it a danger to me or my fish? Is it a parasite? I ask because I have heard that fish can carry tape worms? thanks for any help!