A family friend said: "It was his mum who found him at home. He was apparently playing the 'choking game'.
"Karnel was such a witty and happy young boy and really close to his brother and sister. He was a popular lad at school and had a good word to say about everyone".
The death happened during the half term holidays, and staff and pupils at his school Greenwood Academy are said to be 'devastated'.
Headteacher Harry French said: "The staff at Greenwood Academy received the tragic news of Year 7 Student, Karnel Haughton's passing. Our thoughts go out to his family, friends and the Castle Vale community.
"Karnel was a chatty, witty, mature young man who always had a smile on his face. He had many friends who will be devastated by this sad news."
Police said: "The death is being treated as unexplained and has been referred to the coroner."