He also felt he couldn't leave the wharf because the two men were on the narrow walkway linking the pontoon to land.
"At 4.45pm I received a call from a number I didn't know," Coleman said. "It was [her son] and he said to me, 'mum, some people just pushed me into the water. My phone's broken now'."
When Coleman arrived after dashing to her son's aid, she discovered him soaking wet with goosebumps and missing his slip-on shoes, which came off when he was under water.
He relayed to his concerned mum how one of the men had approached him under the guise of a fishing query.
"The man went up to him and said, 'can you show me how to cast'."
Her son obliged and stepped to the side to demonstrate the skill, only to be suddenly shoved off the pontoon and into the tide.
"We're lucky because my son can swim, but if they'd pushed off a person who was unable to, things could've been a lot worse," Coleman said.
When he finally surfaced he spotted the men running away with the puppy still in their possession.
Coleman said another fisherman had helped her son out of the water.
Whereupon the teen realised the pair had taken the $30 from his wallet.
"Which, since he's not working, is a lot to him," Coleman said.
Despite the incident, the philosophical teen has assured his mum that he won't be put off fishing – a hobby he has enjoyed since he started aged 18 months.
And despite Coleman's frustration that places in Whangārei where youngsters should be able to feel safe failed them, the Whangārei-based counsellor recognised it could be a sign of bigger problems.
"I'm upset that it happened but I understand that when you feel powerless in your life you do things like this ... it takes being shown empathy to be able to show it to others who are more helpless."
The family had not reported the incident to police or the SPCA because they felt they did not have enough information that would help net the pair.