كتب : Hatem Maher
Iraqi striker Mostafa Karim broke the deadlock four minutes after the break before Mohamed Fadl doubled the lead eight minutes later.
Midfielder Hosni Abd-Rabou, who was cleared to play for Ismaili after a wrangle over his rights between the Dervishes and Strasbourg, completed the rout in the 59th minute.
Ismaili, who stunned Zamalek 1-0 in the league opener, top the standings with six points while Tersana lie tenth on three points.
Karim, who arrived in the close season from Iraq's Arbil and made an instant impact by scoring the winner against Zamalek, put the home side ahead in the 49th minute.
Sayed Moawad's cross was chested by Fadl into the path of Karim, whose low shot went into the bottom corner of the net.
Fadl turned from provider into scorer in the 57th minute after sending another low shot past the advancing keeper Ahmed Saad.
Abd-Rabou concluded the score line two minutes later after curling a superb shot from the edge of the area into the right top corner of the net.
Elsewhere, Arab Contractors edged past Alexandria-based club Ittihad 2-1 away from home.
Ehab Al-Masri scored twice for Arab Contractors while Youssef Hamdi scored Ittihad's consolation.
Hassan Mousa's strike led Al-Gaish, who finished fourth last season to play in the Arab Champions League, a 1-0 victory over Masri.