Catch kangarats is a mission in Jak 3. Kleiver requested Jak to use his leaper lizard to catch six kangarats that had been raiding his storeroom, in return he would allow them to drive one of his buggies.
The PlayStation 3 and Vita versions of this mission are related to a trophy named "I Smell A Rat", completing this mission will reward you with a bronze trophy.
The first mission inside Spargus as well as the first time on a leaper lizard, this one has you running around a lot. There's a total of six kangarats (easy to find by using the map) scurrying around the place and they have to be caught with your mount.
Technically they're all slightly faster than you are so you're forced to use the leaper lizard's charge attack to cut the distance when close enough. To get close enough however one will need to cut corners and use the lizard's maneuverability to their advantage. A cutscene will commence automatically when a kangarat is hit, showing it being gobbled up by the leaper lizard.
It is technically possible to kill one with melee attacks, however this means you need to corner one (preferably in the street leading to the Garage) and get close enough to force it to run past you to escape. Similarly you can also rolljump after it and hit it with the Scatter Gun.