n medium amphibious animal 

Perception +5; tremorsense 30 feet

Skills Athletics +8, Stealth +7

Str +4 Dex +1 Con +3 Int -5 Wis +1 Cha -5

AC  17; Fort +9, Ref +7, Will +5

HP 32

Speed 5 feet, swim 20 feet

Melee [>] mouth +10, Damage 1d4+6 piercing plus Grab

Blood Drain [>] Requirements The giant leech has a creature grabbed or restrained; Effect The giant leech drains blood from the creature it has grabbed. This deals 2d4 damage. A creature that has its blood drained by a giant leech is drained 1 until it receives any kind or amount of healing.

Bestiary 2, page 156.