Manly coach Anthony Seibold confirmed Paseka had ruptured an achilles tendon after the 197 centimetre Tonga international stumbled into a tackle in the first half at Brookvale Oval on Sunday.
Seibold said Paseka would undergo surgery on Monday morning.
"It's really disappointing for Taniela. He's been the starting front-rower since I've been at the club," Seibold said.
"He'll be missed, but he'll have the operation and we'll make sure that we get around him."
But even without their most damaging middle forward in Paseka and first-choice fullback Tom Trbojevic (hamstring) the Sea Eagles easily handled the Green Machine.
Centre Garrick chalked up a 28-point haul for Manly, scoring four tries and kicking six goals from seven attempts after his fiancee Riley gave birth to their daughter on Saturday.
"What a 24 hours, huh? It's a great experience for him and Riley as first-time parents" Seibold said.
"I think he can be a really elite centre and a great goal kicker."
Garrick's rampant night brought Canberra back down to earth with a bang.
The Raiders had begun the season on fire, knocking off the Warriors in Las Vegas and pummelling Brisbane in round two.
Canberra thought they were off to another strong start when Seb Kris crossed for the opening try of the game, only for his effort to be ruled out for an obstruction.
Against a lopsided first-half penalty count compounded by errors from their back three, the Raiders struggled for territory and possession.
Corey Horsburgh's 22nd minute sin-binning followed sustained ruck infringements from an ill-disciplined Raiders outfit, which opened the floodgates for Manly.
While down to 12 they conceded 22 points with Garrick, Jake Simpkin and an Ethan Bullemor double putting the home side well on top.
Even at full complement, the Raiders were out on their feet and Manly took advantage with Garrick adding his second try to give his side a 30-0 lead at halftime.
"I'll sound like an idiot but at half time, they had scored two tries from dummy half, which is probably poor organisation at the ruck and or fatigue," said Canberra coach Ricky Stuart.
"Two were off kicks out of the 30 points.
"So defensively, we did a sound job. They should have been 50 or 60 (up) at halftime but well done, they won and we didn't, but I just don't get the first half."
The hosts continued to poke at the sore points in Canberra's defence as Garrick brought up tries three and four early in the second half.
Kris and Hudson Young crossed in the final 20 minutes to ensure the Raiders did not go home scoreless.
