The yellow bar on your pet's GUI represents its hunger. A full bar means a well-fed pet. The lower the hunger points, the hungrier the pet. All pets, regardless of level or type, have a maximum of 100 Hunger Points. Hungry pets need to be fed. You will need to feed your pet stones. Stones are acquired from mining or you can purchase them from other players. Different qualitis of stones restore different amounts to the yellow hunger bar. You can feed stones to your pet by double-clicking the stone's icon in your inventory, or you can drag the stone to a free quick slot. If you fail to feed your pet regularly, it can affect your pet's sympathy with your character and decrease the effectiveness of the pet's skills. If your pet's hunger reaches zero, your pet will refuse to move until you feed it.

How much and how quickly your pet's hunger decreases can vary based on the level of the pet and the level of the character that equips it. While your pet is of the same level or lower as your character, its hunger points will decreases at a normal rate (approximately 1 point every few minutes). If you equip a pet that is of a higher level than the character that equips it, the hunger will decrease at the same rate, but the amount decreased will be higher. For example, a Level 15 character equips a Level 25 drake (a difference of 10 levels). Every few minutes (approximately 5 minutes in real time), the hunger will decrease by 10 points instead of 1. The more levels between the character and the pet, the more hunger points it loses each time.

Hunger Guide
The following is a rough guide on pet hunger when there are differences in levels between the pet and the player.