SYDNEY, Australia — There must have been something fishy about the way she walked. Customs officials said Monday they stopped a woman as she arrived Friday in the southern city of Melbourne on a flight from Singapore and found 51 live tropical fish allegedly hidden in a specially designed apron under her skirt.

“During the search customs officers became suspicious after hearing ‘flipping’ noises coming from the vicinity of her waist,” the Australian Customs Service said in a press release. “An examination revealed 15 plastic water-filled bags holding fish allegedly concealed inside a purpose-built apron.”

The species of fish was not immediately known, but customs officials warned they could carry diseases that could decimate Australian fish if they escaped into local rivers.

Customs officers will charge the woman once they establish what species the fish are. If convicted of smuggling wildlife, she faces a fine of up to U.S. $83,617 and could also get a prison sentence of up to 10 years.