Small Lizards are Slayer monsters that require level 22 Slayer to kill. Ice coolers are required to kill them, which can be bought from any slayer master. They can be killed on desert lizard slayer tasks, along with level 24 Desert lizards and level 110 Lizards, also found in the same area.
Ice coolers must be used on them when they reach 1-120 life points in order to kill them. If an ice cooler is accidentally used when the desert lizard has more than 20 life points, it will still be used up but have no effect. Players would be wise to bring a few extra because of this. Waterskins (and a means of filling them, such as a knife for cutting cactus or Humidify) or an enchanted water tiara should be brought to avoid dying in the desert due to heat. Desert clothing may be useful if you can afford to fight without decent armour. Magic attacks appear to be effective, particularly fire spells, although melee works well enough.
If on a task Level 110 Lizards should be killed for the most experience, as they have more life points. These can be found near to the small lizards. These drop big bones, so more experience in slayer, combat, and prayer is gained than with the smaller lizards. Killing small lizards will allow you to complete the task more quickly, however.