As of current information on the TLP, Phinigel server which is on Luclin ...
They revamped the fire pets a little while ago to do 50% less melee damage, but to cast a single fire nuke often and it self roots while in combat, making it difficult to move it around mid fight.
Basic info (rough estimates):
-HP: 1500
-Damage Shield: 49
-Melee Dmg: 25 (quads pretty often)
-Spell Dmg: 460 (can chain cast this sometimes every 2 or so seconds for amazing burst, longest i have seen it go w/o casting is about 10 seconds)
-Does not seem to bash or kick
I've tanked with this pet, with the level 52 pet heal, in Old Sebilis, Grigg's End, and the lower dogs area in Velks. While definitely not the tankiest pet, the DS and nuke add so much damage most of my time was just spent healing, and kill speed was still decent.
IMPORTANT NOTE:
Make sure you Malo every mob this pet is attacking. The nuke can be resisted pretty often which will drastically decrease its effectiveness. I've seen differences between this pet doing 50 DPS without Malo, to upwards of 200 DPS with Malo. It's mandatory.