Animal cruelty or Medical/cosmetic bliss?

Today i heard a debate on the radio about a wellnessfarm where they make use of Garra rufa or Doctorfish, a small fish that nibbles/suck dead skin of psoriasissufferers.
Not only the psoriasissufferers, also people who just want smooth hands and feet, visit the farm.
The debate was about whether this was a case of animalcruelty, yes or no.
The farmholder said no , “It’s what these fish do, they go to these peoples bodies voluntarily.”
The (political) party for animals(rights) said yes, “You are abusing the fish for your (financial) benefit.”
What’s your view on this?