How often do you clean a betta fish tank?

it really depends on the size of your tank and the capacity of your filter....i have a 10 gallon tank and a 10-20 gallon filter so i clean mine once every 2 weeks...if you want your tank to remain crystal clear all the time, clean it once a week....mine gets a little bit cloudy by the end of 2 weeks.....really its up 2 you but atleast 1 every 2 weeks is recommended....