It is the lovechild of Gangnam Style and Crazy Frog – so it was almost inevitable that merchandise spun out of the viral Baby Shark song and video took toy shops by storm.

Demand for a range of the battery-operated singing toy sharks is so high that the first container load will have sold out online before they even arrive in the UK next month, according to the toy chain The Entertainer.

“The last time I saw anything like this was Crazy Frog,” Stuart Grant, the retailer’s sourcing director, says. In 2005, the Crazy Frog ringtone famously outsold Coldplay’s Speed of Sound as Britons raced to purchase the ringtone with its distinctive “a ring ding ding” hook.

The Baby Shark song is not new but has resurfaced after a 2016 cover version went viral over the summer, thanks to people posting videos of themselves performing the accompanying dance on Facebook.

Produced by the South Korean children’s entertainment company Pinkfong, the English language version of the song and dance video has close to 1.8bn views on YouTube.

“Social media means things can catch on like wildfire,” says Grant, who has ordered 125,000 Baby Sharks but is worried all the shipments will not arrive from Asia before Christmas. He is working with the toy maker WowWee, which is also behind the Fingerlings toys, to secure more stock because it logged 20,000 orders days after listing the toys on its website. He warned: “We’re definitely not going to have enough stock to meet demand as it stands.”

Grant predicts the toys – with the cheapest selling for £7, rising to £25 for a model that gyrates in time to the music – will be among the most-coveted this Christmas. Strong Christmas trading is crucial to the success of The Entertainer, a family-owned chain where profits jumped 38% to £11.9m in 2017.

Baby Shark has blockbuster sales potential. In South Korea, the merchandise is a $100m (£76m) business that spans soft toys, T-shirts and duvets.