They described Kayden and his twin brother, Jayden, as "the two musketeers".
Kayden accidentally fell into the fast-flowing water near Skye Park in Ballymena at around 1pm on Saturday and was quickly swept more than four miles downstream.
A major search and rescue operation was launched and the boy was recovered from the river and airlifted to the hospital but he was declared dead shortly afterwards.
Kayden's parents, Darrel and Leanne Fleck have described their "happy-go-lucky" son as "your average wee boy" who "just melted your heart".
'The five-year-old boy fell into the water at around 1pm today.
"NIAS dispatched an A&E crew, a BASICS doctor and the Air Ambulance to the scene to assist in a multi-agency search and rescue for the boy".
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The child was then flown to Royal Belfast Hospital for Sick Children, where he died of his injuries sustained.
The child's school, Harryville Primary School, has asked for everyone to remember his family in their prayers.
'The whole school community is remembering you at this sad time'.
As news of the tragedy unfolded the young boy's school was inundated with condolences for his family.
Police launched a large-scale search operation around the Braid River on Saturday to try and rescue the child.
CRS regional commander Sean McCarry said the child had been "swept away quite fast with it (the river)" and that "he was travelling quite a distance".