Andy Mangan and George Donnelly scored as Fleetwood opened the season with victory at Grimsby.
The Cod Army dominated the first half and James McKeown saved long-range shots by Magno Vieira and Alan Goodall.
Michael Coulson and Antony Elding had chances for Grimsby but Mangan finished tidily from Scott Brown's ball.
Liam Hearn and Scott Garner squandered good chances to level and substitute George Donnelly converted Richard Brodie's pass from close range.
Grimsby: McKeown, Silk (Wood 43), I'Anson, Garner, Ridley, Disley, Thanoj (Artus 70), Makofo, Elding (Spencer 70), Coulson, Hearn. Subs Not Used: Pearson, Eagle.
Booked: Spencer, Wood.
Fleetwood Town: Davies, Barry, Flynn, McNulty, Edwards (Seddon 68), Atkinson, Goodall, Scott Brown, McGuire, Mangan (Donnelly 80), Vieira (Brodie 54). Subs Not Used: St Louis-Hamilton, Cox.
Goals: Mangan 57, Donnelly 90.
Ref: Tony Harrington (Cleveland).