Well I did see a red worm in my moss yesterday, which I removed immediately with a turkey baster. I was sorta looking for something tho, cuz just before I found him I saw a fry suddenly drop from the moss and it was twitching and unable to hold itself up or swim around with control. The fry looked a week old or so as it had some color. I didn't take a photo of the worm yesterday, but it didn't look quite like any photos I'd seen of planaria, about 2mm long skinny 'kinda' reminds me of bloodworms but smaller.
Unfortunately the tank is far too small for any kind of fish.