Penna was formerly coaching the Sea Eagles' Toyota Cup side, while Parish joins the club after a short stint as head coach with UK Super League side Salford City Reds.
Manly's first graders returned to training this week after a tumultuous off-season in which former coach Hasler was dismissed.
Hasler's right-hand man Kelly Egan joined him at the Bulldogs.
Toovey was keen for the players to shift their focus to on-field concerns.
"The sooner the ball gets kicked off, the more we can live in the present rather than the past," Toovey said.
"The players are very committed and supportive of myself and the other coaching staff."
Manly captain Jamie Lyon said pre-season training had a sense of familiarity about it, even with the change at the top.
"We've got a few new faces out there amongst the staff and players. Everyone's keen and looking forward to the challenge," he said.
- AAP