Matt Wash 
Search for the Golden Piranha [EPUB ebook] 

The Thistle family arrive in Rio, Brazil, full of excitement about the dream holiday that awaits them.However, when a planned day out at the water park (or a museum for dad, Colin) gets interrupted by the Blood Knife Gang, things quickly take a turn for the worse.Encountering many nerve-wracking twists and turns along the way, the Thistles just hope that they can survive all the challenges that the jungle has in store for them.