Answer To Which Taanis

The Sha’arei Teshuva (O. Ch 580 ) writes, they

 found the Pinkas (Kehilla Records)  and in it was

written,“They were Gozer Ta’anis, כ' סיון only for

males older than 18 yrs. and females older

than 15 yrs.”

This is in accordance with the Magen Avraham

(576:10) who writes, “When we are Gozer Ta’anis Al

Kol Tzoroh Shelo Tavo, The minimum ages for fasting,

are 15 & 18 years."

The ד' צומות we start at ages 12 &13 but  all the others

we start at ages of 15&18