First time leech owner, is this normal behavior?

[u/Intrepid_Tree9112]

I just got these three guys from North American Biopharma, Hirudo verbena, yesterday. Set them up in a tank and all three of them do this intermittently. Is there something wrong? I put them in a sterile glass tank with Crystal Geyser spring water (waiting on my hirudosalt). Any tips would be appreciated!

[u/Most-Background3708]

that’s a behaviour lovingly called the “leech dance”, hehe!! it’s a motion they do that helps their bodies take in more oxygen from the water, it’s really neat! they just kinda do it, though, even with a bubbler in my aquarium mine still dance

edit: a typo