Freshwater Parasite?

Hey guys! It's been awhile since I've posted, the good news is I have finally gotten a job and now things are looking up, however in the midst of chaos all of my SW babies have passed T^T SO the tank they were in is now hosting my freshies. I have cleaned out ALL of the sand from prior and rinsed tank out numerous times. Anyhow I need some insight on parasite ID.

Some background -

I put them in a tank decorated with red flag-stone and rocks from the established tank prior. The tank prior was a gift from my teacher who believed in more natural "let the tank do its thing" and it was as algae filled as ever o.o. When I got the rocks and rinsed them the water resulting was black as can be. Needless to say that was a long rinsing process x.x The rocks also hosted a large colony of snails that have made many generations that are too many to count. Now I have ruled out algae since some light hits the tank (but not too much) but was a significantly lighter shade of green than whatever hellish fiend spawned in my tank. My rocks got what looked like a dark moss to start covering them so I took my tank cleaning handy dandy toothbrush. The Green Fiend wouldn't scrub or scrape off. -.-

Shortly following my fish began to get covered in what looked like ICH but after many a fish death and weeks of treating I moved towards treating for a fungal infection and quarantined outside the display. (I treated the display since rocks were odd as I said before) My fish have perked up significantly and the tank has been running fishless for about a week. With the fish gone, all the snails have emerged out of hiding and are everywhere cleaning up. But I also noticed what looks like elongated white specks/worms that I can only describe as a snail with no shell. Which makes no sense, because I have smaller snails with shells. My camera doesn't pick them up since they are so tiny. They reminded me a lot of copepods, but I wasn't sure if there was a freshwater equivalent. Has anyone seen any similar critters?


Prior Inhabitants (Prior to death) (120 gal tank)

1 Kissing Gouriami (passed)
1 Gold Gouriami ( Alive and well)
1 Dino Bichir (passed)
1 Monster Chichlid (very non aggressive for a cichlid)
5 Goldfish (3 have passed)
1 frog (passed)
7 guppies (all passed except 1) I also saved 3 baby guppies which were separated prior. Guppies were separated from cichlid.
1 pictus catfish (passed)
1 Plecostomus (alive and stubborn)