Blue Fire

From Zelda Wiki.org

In Ocarina of Time, Blue Fire can be found free of charge in Ice Cavern and Ganon's Castle, or for 300 Rupees at the Magic Shop in Hyrule's Market as a child or Kakariko Village as an adult for 300 Rupees. In any case, an Empty Bottle is needed to store it. The only function of the uniquely-colored fire is to melt Red Ice.

The Blue Candle from The Legend of Zelda is similar in appearance to Blue Fire, but the two items are very different in function.