A vigil has been held in the park where 13-year-old Carson Price was found unconscious before later dying in a suspected drugs-related death.
Carson, of Hengoed, Caerphilly, was pronounced dead after being found in Ystrad Mynach Park on Friday.
Hundreds of people gathered to release balloons in his memory.
Earlier on Thursday, Gwent Police officers arrested a 14-year-old boy on suspicion of supplying class A drugs in connection with Carson's death.
The force said the boy was arrested in Pontllanfraith, near Blackwood.
Gwent Police is trying to trace Carson's movements prior to his death, while a form of MDMA - known as Donkey Kong pills - is also a line of inquiry.
The force said it received a separate report that a man became "seriously ill, requiring hospital treatment" from Donkey Kong pills over the past week.
Supt Nick McLain said: "The community are telling us that they have growing concerns about this drug and we want to do all we can to make people aware of the dangers."
In a statement released at the vigil, Carson's family said: "On Friday our lives changed forever when our little boy was taken away from us.
"Carson was bright and caring, kind and loving. He was a cheeky little boy. He was the best big brother to Coby and was loved by so many.
"We have been truly overwhelmed by the support we have received locally, nationally and from around the world.
"Thinking of another family going through what we have is unbearable. We urge people to talk about the devastating consequences that drugs can have and how they destroy lives.
"Parents, please speak to your children, or if you are young and need help, there are people a that can give you advice."
Rachel Joynes, attended the vigil and said her three sons, aged 10, 11 and 13, were close to Carson.
She said: "He brings a smile to your face when you think about him. It's a sad moment but you can see how much people cared and loved him, they have come from everywhere.
"We are here to pay our respects to a much loved boy in the community and support his parents and family to celebrate his life."
Caerphilly county borough mayor Mike Adams said: "We want everyone to leave with a good memory of a life lost. He was a nice lad with a future, so sad it had been cut short.
"The message is not to take notice of peer pressure and be yourself. Be yourself throughout your life."
Gwent Police Supt Nick McLain said: "The information received from the public has been a vital part of the investigation.
"I would like to emphasise no-one has been charged with any offences and the investigation is still continuing.
"I'd like to ask the community to support our ongoing work and refrain from posting any comments on social media that may jeopardise the investigation."