Mermaid tails have been banned from Auckland Council leisure centres and pools because of safety concerns.
An announcement on the Stanmore Bay Pool and Leisure Centre Facebook page tells visitors: "We wish to advise our customers that ALL mermaid tails and fins are no longer permitted in any Auckland Council leisure facility.
"The ban is in response to the dangers associated with the products: They hinder the ability for children to move their legs while swimming [and] they promoted prolonged under-water swimming which can lead to shallow water black-outs."
Mermaid tails are an aquatic device that mimic the body of the mythical creature. The user slips into the fin as if putting on pants. Their legs are bound together within the tail device.
The fins have become increasingly popular around the world with adults and children.
The tails - available in different colours and designs - give the illusion of a mermaid swimming in the water; with a swimmer's legs bound inside.
A widely shared YouTube video from last year shows how much of a danger they can be to children.
Many people have supported the new ban, dubbing the mermaid fins dangerous.
Kelly Davis wrote: "Dangerous, stupid toy. Water is dangerous enough without restricting the poor kids' legs."
Someone else labelled the devices "shocking toys" and another parent said: "It's basically like swimming with your legs tied together."
But other members of the public were upset for a different reason -- saying having a blanket ban on the devices was unfair to those who used them safely.
Rachel McDonald said it was "PC gone wrong."
"Well this absolutely sucks. There is a website associated with the sale of these products which issues both swimming tests before being allowed to use them -- followed by swimming tests in the fin before you are allowed to let them swim.
"So following all safety precautions and having an adult getting into the pool with them still isn't enough?"
Auckland Council leisure manager, Rob McGee, acknowledged the popularity of the mermaid tails and suits over the Christmas period.
But they were asking parents to keep the devices at home so they could guarantee one-to-one supervision of their children.
"We are all for everyone enjoying their time in the pool and would like them to do so safely."
Mr McGee pointed to similar bans overseas; specifically in the United Kingdom and more recently in Australia where safety concerns had also been the big issue.
"While they are designed for competent swimmers to use in the water, even the manufacturers recommend one-to-one supervision -- which we can't give in public pools," he said.
"So far, most pools have only seen one or two mermaids.
"But given overseas experiences, the focus on isolated swimmers puts other pool users at risk, so we are asking parents to keep the mermaid tails for home pools where they can have the direct one-on-one level of parental supervision."
Kerry Anderson, aunt of Eden McPherson, 7, who is from Rotorua but has moved with her family to Australia, says Eden uses a mermaid tail and that banning the tails could be dangerous.
"For those who don't have a pool at home, the ban may force them out into beaches or lakes where kids may get dumped by waves or tangled in weed.
"Even though Eden is a pretty capable swimmer, we still have fears because we've seen the YouTube videos of children involved in mishaps. The only time she's allowed to wear her tail is when an adult is in the water alongside her and within arms reach and that's easier to do in a pool.
"It would be so much harder to supervise a child with the fin in an open beach, lake or river."
Ms Anderson said the first time Eden wore her tail and fin was at a surf beach with her mum and aunt next to her.
"Although she didn't have any problems on that occasion we all prefer to take her to a local swimming pool to play. We've used a GoPro to view her swimming ability underwater and she seems fine but we'll always be cautious.
"Eden knows she isn't allowed to try forward flips in the water while she is wearing her tail and fin but she will try to test the limits.
"There should definitely be rules for them in public pools based on courtesy to other swimmers, but a ban seems harsh.
"Maybe the pool could introduce a no-adult no-fin rule, or a swim test where a child has to swim the lap of a pool before they can wear them in their facility."
Ban 'not a surprise'
A spokeswoman for Mermaiding NZ said the ban was not a surprise, but somewhat sad because it was unfair for capable and strong swimmers who used the mermaid tails correctly.
"If there's a craze, they can embrace it. What I'd like to see is a few sessions for mermaiding and having an adult in the pool as well -- I think that would be a great success."
The spokeswoman, who asked not to be named, said she had sold up to 20 full mermaid suits -- which includes a monofin attached to the feet and a lycra suit covering the legs -- in 2014.
She bought the suits from the United States for about $150 each and sometimes made the lycra outfits herself.
They had been particularly popular with parents shortly before Christmas that year, she said.
"Then when more requests came in, I realised I didn't know the people who were buying them and if they were good swimmers, so I stopped selling them."
Her own children were very good at using the fins and suits together; but she warned parents should not buy them if their children were not confident in the water.
"Anything around water always needs to be monitored and supervised."