I just discovered my little guppy, Holden Caufield, dead

in my tank tonight when I went to feed the fish. I noticed him in the same place about an hour ago when I started my dishes and when I got done, about 30 min. later, he was still in the same place. I thought it was strange but thought maybe he was just sleeping already but when I got to feeding them, I noticed his eye looked a little funny and there was this fuzzy looking stuff around him. He'd been laying on one of the plants but when I got my net to see if he'd move, he floated right to the top and all the fuzzy stuff started floating around him into the water. I got him out and started looking at him and I noticed that there are a couple of brown spots on his tail and underneath him close to his head, looks to be a red spot. Now, I've been checking on my fish several times a day as I've got some mollie fry (see recent post "I got baby fish" under Breeding) but I know Holden was fine all day today because I would've noticed if he'd been sitting on that same plant all day. And although, I don't know for sure, but I don't think he would have gotten fish fungus in one day and me not notice it. I have been very careful with my water and everything since my other guppy Mr. Darcy, died of dropsy. And I can't believe if Holden did have fungus, he would have died within a day of it showing up on his body but, there again, I have been watching them all very closely since the arrival of the fry and I would have noticed the fungus if it had been there.
I am wondering if the other new fish killed him! There are two mollies and a platy and they are bigger than Holden but I haven't seen them nipping at him or anything. They are all supposed to be non-agressive, tropical community right

Friendly fish

Does anyone have any experiences like this, tropical fish killing another tropical fish??
It's just so odd. I have had him almost a year and even through all the problems I had with my other guppy, Mr. Darcy, Holden never got sick or anything. I just know that somehow these other fish had something to do with his death!!! It might seem silly to some but I get very attached to my pets and I consider these fish my pets. I am very upset right now....
