In The Legend of Zelda: Ocarina of Time for Nintendo 64, the Sage of Fire is the Goron leader, Darunia.
Light Sage: Rauru the Hylian Priest Forest Sage: Saria the Kokiri Girl Fire Sage: Darunia the Goron Elder Water Sage: Ruto the Zora Princess Shadow Sage: Impa the last Sheikah Spirit Sage: Nabooru the Gerudo Princess but, you dont really need to know WHO they are in order to proceed, they reveal themselves after you've beaten their temple.
saria
The Third Sage is Princess Ruto of the Zoras, the Sage of Water, who you rescue from the Water Temple.
The seventh sage is actually Princess Zelda. She is the Sage of Time.
Set fire to it.
water temple
If you mean Temple, then all 5 temples in order are: Forest Temple, Fire Temple, Water Temple, Shadow Temple, and Spirit Temple.
After you beat Ganon in the Forest Temple, Saria will appear and say she can no longer be with you for she is the Forest Sage.
Fire Temple
In the ocean temple, Or water temple, You collect the longshot, And the Water Emblem, You also awaken the Sage, Princess Ruto who adds her powers to yours.
Fire Temple
Fire Temple.