Callahan added four steals while Tarrant had five assists. Josh Davis had 11 points and eight rebounds for the Green Wave (7-2).
Freshman T.J. Carpenter notched a career-high 15 points for the Colonels (1-4).
The win makes Tulane 4-0 on its current homestand, and the Green Wave has now won 19 of 20 all-time showdowns with Nicholls State.
Tulane led 23-12 with just under 8 minutes left in the first half, but the Colonels cut the lead to 30-24 by halftime.
Callahan hit a 3 then Davis made a dunk and two free throws to put Tulane up 37-24 after the break. Nicholls State never pulled closer than eight after that.
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
|Stephen F. Austin||18-0||-||28-6|
|Sam Houston State||12-6||6||18-16|