Sorry gents but I'm gonna try to get this back on track.
Jodie, there's plenty of resources out there with Classic information about mage pets. Now sadly our beloved emulator doesn't work EXACTLY like Classic but I know that Wenai and the other devs have gotten us as close as possible to it.
Check these out to better help you understand how the pets work and why they would be nerfed/buffed/etc.
EQSummoners:
http://www.xalmat.com/eqsummoners.com-old/eq1index.html (Pets > Statistics > Each specific pet link has a lot of raw information on them)
EQ Magician Resource:
http://www.watson.org/~wander/eq/elementals.html (Awesome simple run down of the pets)
And as someone previously stated, the fire pet's AC was nerfed since their survivability was far too high, and to be honest still is even after the nerf.