What the heck is this??!!

[BionicBroccoli]

I have a snail only tank used for breeding snails for my Fahaka Puffer and as I’m getting ready to do my water change I see this thing?
Also are my snails safe?
I am holding off on using them as food for my fahaka as this scared me.
Could not get the video uploaded so I am adding some screen shots.

 

[duanes]

I edited you photos a bit to try and get a closer look, in the shot below, it looks like a leech.
Your puffer may eat it.

 

[kno4te]

Agree with the leech ID.

 

[altums85]

Looks like those common leeches that comes when u buy live blackworms.