Are you asking how many inverts it would take to cycle a 125? If so, the answer is none
There are several ways to cycle a tank, dead shrimp, damsels, ect. but the easiest is to introduce live rock and live sand which is full of the bacteria needed to establish a tank. This route is much faster than the above methods, and you wont have to go chasing after mean little damsels when its over
HTH