This hunt becomes available any time after you have completed the Ancient City of Giruvegan and the Great Crystal. You should return to Balfonheim Port to speak to Reddas and have him join your party before starting this hunt as having Reddas in your party will be helpful.
The petitioner is War-chief Supinelu. You have visited War-chief Supinelu a few times in the past and likely know where to find him, but if not, he can be found in Jahara in the Lull of the Land area.
Catoblepas is located in the Zertinan Caverns. Warp to the Dalmasca Westersand and enter the Zertinan Caverns through the Shimmering Horizons area. This will take you to the Invitation to Heresy area of the caverns.
Travel south into the Sandfalls and south again into the Hourglass Basin. This is the area where you will find Catoblepas but you will have to enter from the secret passageway located in the next zone – the Undershore. Head south and save your game at the Save Crystal in the Undershore and then follow the secret passageway back into the Hourglass Basin.
War-chief Supinelu will join you when you re-enter the Basin - Catoblepas is located at the end of this pathway.
Level: 46
HP: 187,991
Steal: 
Hi-Potion (55%), 
Beastlord Hide (10%), Gemini Gem (3%)
There is not too much in the way of strategy required to defeat Catoblepas. He does deal a hefty amount of damage though which means that you should begin this battle fully prepared and with all enhancement spells enabled. Equip all of your characters with 
Bubble Belt and cast 
Protect, Shell, Bravery and 
Haste on all of them.
Set up one of your characters with a Dispel Gambit to remove Haste when he casts it and set up a Gambit to cast and keep 
Blind on Catoblepas for the duration of the battle. This will greatly reduce the amount of damage done. His attacks are all physical-based so make sure to equip your best armor and shield to your tank and you should have no trouble surviving the onslaught.
Return to the Lull of the Land area of Jahara and speak with War-chief Supinelu. He will tell you a short story about how his brother fell to the beast before giving your rewards for completing the Hunt which includes 3,200 gil, a 
Volcano and an Arctic Wind.
