"People are calling him the next Jonah Lomu, but we think he'll be a concert pianist."
Doctors had predicted the boy could weigh close to 14 pounds (6.4kg) but his eventual size surprised everyone.
It is the mother's second boy. Her first child weighed 11.8 pounds (5.4 kg), Fairfax said.
A child born in Hamilton in 2014, weighing 15 pounds, 1 ounce (6.85kg) was believed to be the previous record holder.
The heaviest baby in the world weighed 22 pounds (a little over 10kg) and was born to giantess Anna Bates in 1879, according to the Guinness Book of Records.