Police and family members joined the search and were assisted by a local jet boater and the rescue helicopter.
Valentino's girlfriend Stevie Kumeroa told RNZ that Valentino was a free-spirited person.
"He's a cool type of guy, he loves being out there. He's not shy at all, he's really sporty and loves rugby."
Meanwhile, Ateliana Laki told Stuff her adopted son could not swim.
"We don't think it's happened. It's a real shock," she said.
Valentino had been living in New Zealand for only nine months.
Before the teen was discovered, Rangitikei District Mayor Andy Watson said people often got caught when river levels were like they are now.
"There's a lot of logs and willow trees that either get swept into the river, when the river's high, or they're on the banks."
He said his heart went out to the family.
Rangitikei College teacher Marise Taru said she taught Valentino in the final school term of last year.
She said he was a happy and adventurous young man who had recently moved to New Zealand from Samoa.
Taru said she was devastated when she heard he was missing.
Students often swam at the spot he disappeared from but described the trees on the side of the river as a "danger zone", she said.
"It's fun and enjoyable until it's not, it can happen really quickly.
"I don't know if he's swum there a lot, I've seen him in a pool at school and he was always laughing and splashing around and having heaps of fun. I can imagine he wouldn't have even contemplated the consequences of a swollen river."
The matter will be referred to the Coroner.
