Are these leeches?

[Plec123]

Hehe, yup those are leeches.
I might be overly cautious here, but I wouldn't feed live leeches to your fish. Who knows, they might survive and cling onto your fish's throat or intestine.

True.

 

[SeaweedPimp]

holy ****

 

[nikond70s]

there common when you buy live blackworms. from my experience there harmless. there chewy tho but my fishes do eat them. they get pretty big. cleaned my substrate one time and saw a survivor it was like half and inch long....pretty creepy looking.