Parasite on fish?

Question
I sent this to another expert but they sent it back saying they couldn't answer it so I hope you can.I have a 35 gallon tank thats been set up for about 3 months before that I had a 10 gallon tank but I was having a problem with snails so I completely got rid of that tank and everything in it.I have no live plants in the current tank and feed my fish  dried shrimp,  dried bloodworms and flakes. In my tank I have dalamation mollies, guppies, gold cloud dannios, and harlequin hets. All my fish seem to bedoing well except I am losing guppies at about one a week. They get lathargic where they just lay somewhere. Two of them had eyes that turned totally black before they died but the other didn't. Today I was checking on all my fish when I noticed that one guppy had something attached to its tail. I got out the net and slowly brought it out of the water then ran my finger down its tail. When I realeased it back into the water I looked at what was in the net that I got off its tail. It was a worm of some sort about the size of my pinky nail(I have extremely short nails). It looked black. After checking more of my fish I realized that all of my fish except the danios had at least one worm on it. The worms attach either behind their fins or on their tails. I did get new fish about a month ago from Petland so I am assuming the problem may have came from there. I did not see it having a forked end like some parasites do but then they are so small that I may have just missed it. Can you tell me what these are and if there is a nonchemical cure for it. If there is not a nonchemical cure then what would best chemically cure it. Thank you.

Answer
Hello,
I have never heard of anything like this but your best bet is its coming from either the new fish or a parasite from a bug that has decided to lay its eggs in your tank, i had a moth lay its eggs in my tank, it was a speciel species who's catapillars actually live in water, annd they look like catapillars.

You need to do a 50% water change and then go to your local pet store and ask if they have any treatment for these random parasites, explain to them what you have to me.

You may also be loosing your fish due to over stocking, i know you have a large tank, but how many fish in total are in there?

If you cant find treatment turn your temp. up to roughly 30-32 degrees celcius as i find this kills most parasites like white spot, but only do it for about 6 hours. then do another 50% water change 3 days after your originall water change.

Let me know how it goes