They had declared the tail so did not receive a fine.
"The main problem was that the passenger didn't have documents to prove the hair had been treated to kill any bugs in the skin tissue, or any hitchhiking organisms that could harm New Zealand horses or other parts of our primary sector," Mr Spelman said.
The tail would be allowed to enter New Zealand, but only after it was fumigated at the passenger's expense.
Mr Spelman said all passengers should declare or dispose of any item that has a potential biosecurity risk before crossing the border.
"And that's what this guy did. So that's great."