Seafood Delight

I need help, y'all. My new babies are being bad. My black molly was swimming around, minding its own business, but unfortunately, I was minding it; there was a long orange-ish pinkish trail of something following behind it. At first I was like, aww no way, not this one too... (I recently bought two Fancy (fantail) Guppies like this:

and they have been undergoing much bullying by the bigger, scarier fish called the Serpae Tetra). So needless to say, you can understand my reason for thinking that the foreign object trailing my blackie was a strand from one of the Fantails' fan tail.

Then it detatched, and was promptly eaten by the waiting fish below. Surely this could not be a fin. It slowly dawned on me, to my horror, that this lovely delicacy so sought by the neighbors was none other than the lovely leftovers from tonight's dinner. Real poopies!!!

This can't be natural. What is happening??