"It's been home to right-wing extremists, Isis-linked jihadists and there are also consumers of child exploitation that inhabit that space.
"There's not a great deal of moderation. People can occupy that space in any way they want to."
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Richard Sivell, the man who appeared in court this week, was an active user of Telegram and went as far as posting updates to the social media platform in the lead-up to his arrest.
Fisher says that to understand how Sivell ended up with these charges, you have to look at the sphere he occupied online.
"We're talking about people that are largely disenfranchised, somewhat set apart from society," he says.
"They tend to be people who have had a life shock of some sort. They are people who have an uncertainty. The ground on which they stand is not so certain.
"Sivell is slightly outside of the norm in that he's 39, but a lot of anger and expression of violent anger comes from Pākehā men aged 40 and over, who often have small to medium-sized businesses and are self-employed. They're people who don't have security in their lives and they're seeking that security and they often fixate on the reasons that they feel they don't have this security."
Angry language, which may include threats of violence, is common in these groups, but they rarely result in actual real-world acts - making it difficult to separate real threats from hyperbole.
"The sheer volume of violent rhetoric has caused the language to become normalised," says Fisher.
"It's become really hard for security services to discern somebody ... blowing hot air from someone that actually poses a real threat."
Fisher's reporting on the activities of these online communities over the past few years hasn't gone unnoticed.
"I've had more death threats in the last year than I've had in 33 years of reporting," he says.
While the emotional toll does weigh on him, Fisher says it remains important to shine a light on these issues so that something can be done about them.
He also says it's important not to simply dismiss these people as nuts, best left ostracised.
"This is a very broad mainstream form of disinformation. It's getting soccer mums, it's getting dads that volunteer at the PTA, it's getting the bus driver that used to take the kids to school, and it's getting the drama volunteers. It's right throughout the community."
Fixing this, Fisher concedes is not an easy task.
"It takes a lot longer to pull someone out than it does for them to fall in."
Listen to the full episode of The Front Page to hear the steps he thinks we should be taking to address this issue before we dig deeper and deeper into our filter bubbles.
• The Front Page is a daily news podcast from the New Zealand Herald, available to listen to every weekday from 5am.
• You can follow the podcast at nzherald.co.nz, iHeartRadio, Apple Podcasts, Spotify, or wherever you get your podcasts.
