A woman in her 20s reportedly lost all of her toenails after allegedly getting a so-called “fish pedicure,” a treatment touted by many as rejuvenating for a person’s feet.

Fish pedicures involve having small fish nibble on a person’s feet while they soak in a tub of warm or room temperature water. The toothless carp fish – which are plant eaters – voraciously feast on dead human skin.

After having the fish pedicure, the woman said her toenails stopped growing and then started falling off. At first the woman thought she might have onychomadesis, a condition known for having similar symptoms; however, a visit to a dermatologist, ruled that out, Gizmodo reported.

“While the mechanism of action is not entirely clear, it is likely due to the fish traumatizing the nail matrix,” Sheri Lipner, an assistant professor of dermatology at Columbia University’s Weill Cornell Medicine and the woman’s doctor, told the website.

She said the case could be the first documented instance of onychomadesis ever caused by fish.

“I do not recommend fish pedicures for any medical or aesthetic purpose,” Lipner said. “In addition to onychomadesis, there are also serious infections associated with fish pedicures.”

Lipner would not reveal where the woman got the pedicure, but noted the treatment has been banned in at least 10 states, largely due to health concerns.

The woman’s toenails will likely return, but it will take a long time as nails only grow about one millimeter a month on average, Lipner said.