Koekkoek was Tampa Bay's first pick in the 2012 NHL Draft, taken 10th overall. The 22-year-old has one assist in six games with the Lightning this season, and five goals and 10 assists in Syracuse.
Vermin was taken in the seventh round, 186th overall, in the 2013 NHL Draft. He also has one assist in six games with the Lightning.
The 24-year-old Swiss winger has six goals and 11 assists with the Crunch this season.
The Lightning host the Florida Panthers Saturday night at 7:00 p.m. ET. The two teams are tied at 91 points for the Atlantic Division lead.