(GUARDIAN) - Former Ultimate Fighting Championship (UFC) fighter Tim Hague has died following a knockout in a boxing fight.

Hague, 34, was taken to hospital on Friday after he was knocked out by Adam Braidwood during their fight in Edmonton, Canada but died on Sunday.

"It is with incredible sadness, sorrow and heartbreak to report that Tim has passed away today," Hague's sister, Jackie Neil, said in a statement on Sunday.

"He was surrounded by family, listening to his favourite songs. We will miss him so greatly."

The Canadian fought in five UFC contests winning his debut before losing the other four.

In total, he fought 34 mixed martial arts (MMA) contests, and had a 21-13 record.

He was knocked out eight times, with four of those coming within the last two years.

After the end of his UFC career in 2011, he said he was going to take time off after suffering a concussion.

"I'm gonna take a little break away from MMA, let the brain heal from my concussion, and get the passion/fire back," he wrote on Facebook.

On Saturday, before Hague's death, retired UFC fighter Anthony Johnson, who lost to fellow UFC fighter Daniel Cormier in the UFC light heavyweight title fight in April, cited Hague's injury when talking about his decision to quit earlier this year.

"This is a reality check for me!" Johnson wrote on Instagram.

"I've knocked a lot of ppl out and (I don't know) how this didn't happen when I fought. I've been afraid of this happening to me and after learning about CTE (chronic traumatic encephalopathy) I'm afraid of it happening to anybody."

Away from competition, Hague was an elementary school teacher.

"Our hearts are heavy," his principal at Ecole Bellevue School, Jennifer El-Khatib, wrote in a statement on Sunday.

"Mr Hague was a beloved teacher and staff member. His students loved him and looked up to him, and he was an important part of our school community."