Are tattos halal

No, they aren't halal, as narrated in a hadith:

May Allaah curse the women who do tattoos and those for whom tattoos are done, those who pluck their eyebrows and those who file their teeth for the purpose of beautification and alter the creation of Allaah.

Permanent tattoos are not allowed, as they change the creation of Allah, but temporary ones that vanish or can be washed off after a while are permissible.