He said: "He was flapping around like he couldn't swim and his head kept going under the water.
Daniel Peden, who was on an Easter trip to the city from his home in Manchester, became a lifesaver when eight-year-old Ross Hunter became too interested in a toy floating in the Union Canal and fell in.
His head was disappearing under the water and despite being a strong swimmer he could not pull himself out.
But Daniel, who had been feeding ducks nearby, heard the boy's frantic splashing and ran to his aid.
He said: "He was flapping around like he couldn't swim and his head kept
going under the water.
"I ran to a little ledge and tried to grab him. I got his arm and pulled him against the ledge and he pressed his feet against it and was able to get out."
"I felt scared and when I got him out he was spitting water and crying because he'd had such a fright. I took him home and his mum thanked me."
Ross said the ordeal had left him badly shaken.
He said: "I was frightened because I felt really strange with the cold. Water kept going in to my mouth and I would have drowned if Daniel hadn't been there because I couldn't touch the ground."
Ross's mum, Selena, 27, said her son would have died if it has not been for
the heroic efforts of his young rescuer.
Mrs Hunter, of Polwarth, Edinburgh, said: "All of a sudden I heard this screaming and my heart sank. When I saw him I knew there was something really wrong because he is a brave boy and he doesn't usually cry.
"I have taken this as a warning and am never letting him out of my sight again. I am so grateful to Daniel and can't thank him enough."
Daniel, from Manchester, was on holiday and staying with his aunt whose home overlooks the canal when the incident happened on Monday.
Treated with respect
His mother, Deirdre, said: "I am so proud of him. It was such a good thing for him to do because he could have just stood there."
A spokesman for British Waterways, said: "Canals are very enjoyable places but they should be treated with respect.
"You must keep away from the edge at all times, stick to the tow path and take the usual safety measures when near water."