It is basically an experience from some Star Trek pleasure planet, as one sits with ones feet in the fluid and a horde of nanobots (thanks, iOS, for autocorrecting that to manicure) remove your dead skin one cell at a time. The fish are dark brown and have downwards-opening mouths: they come in a wide variety of sizes, from teeny ones that nibble under your toenails to ones the size of small goldfish which prefer the base of the feet. The feeling is basically pins and needles: I am very ticklish and giggled uncontrollably for the first thirty seconds. With the largest ones you can nearly convince yourself that there is anatomy in their mouths. They eat dead skin but not hair; they leave no marks.
I strongly recommend this service: the place isn't terribly busy (indeed, one might call it desperate for custom) and fifteen minutes (or you might prefer to think of it as fifty fish-hours) for fifteen pounds. The advertising for Kismet is more full of woo than the Number Five Happy Military Centipede Factory in Wuxi province, but the fish are honestly toe-nibbling rather than karma-balancing or qi-enhancing or aromatherapeutic.