| skizzerz |
Pathfinder Adventure, Adventure Path, Lost Omens, Maps, PF Special Edition, Starfinder Adventure Path, Starfinder Maps, Starfinder Roleplaying Game Subscriber
Just for pedantry, d20pfsrd is unofficial and may contain inaccurate/incomplete information (they tend to include every sourcebook ever, including 3rd party ones iirc). The official SRD for Pathfinder is found at http://paizo.com/pathfinderRPG/prd/ with the Giant Fly entry being found here or in Bestiary 2.
Pedantry out of the way, I'm not actually sure a PC can have a Giant Fly as a familiar or animal companion without some houserules. It isn't on the list of allowed companions for Druids or on the list of allowed familiars for Wizards (at least, not in any of the core books; they may be present elsewhere but I didn't check all of those).