Guppy nipped tail

[Plecos]

Hi everyone. I have a 70 gallon freshwater tank with tropical community fish. I have 5 glow fish, 5 guppies, 4 glo tetras, 2 platys, 4 cardinal tetras, 3 mystery snails, and 2 julli corii catfish. One of my guppies has been getting his tail nipped. I haven't observed any aggression from any fish except the glow fish but haven't seen which is the culprit. Which of the fish I have are prone to nipping?

Thanks