Belly Up

Belly Up is a 2010 children's mystery novel by author Stuart Gibbs. Teddy Fitzroy and his friends investigate the suspicious death of a hippopotamus.
Reception.
"Kirkus Reviews" stated in its review "Overall, the story is great fun, despite a sometimes plodding approach to the narrative that is too reminiscent of a report. In his authorial debut, screenwriter Gibbs combines details of the inner workings of zoos with some over-the-top action for an entertaining read". "Publishers Weekly", wrote "A likable protagonist, a very kid-friendly brand of humor, and the outrageous setting should keep readers' interest, especially animal lovers". Common Sense Media gave "Belly Up" four out of five stars and said in its review of the book, "At times Fitzroy's voice is a bit more adult-like than one might expect from a 12-year-old boy, and the jokes can be a little dated, but this is a fun, engaging read that moves through suspense as if it written for the big screen." 
Sequels.
"Belly Up" is the first installment in the FunJungle Collection, which takes place at a zoo+theme park in central Texas. Other books in the series are "Poached" (2014), which is about a missing koala; "Big Game" (2015), a threatened rhinoceros; "Panda-monium" (2017) an abducted giant panda; "Lion Down" (2019), a mountain lion falsely accused of killing a famous dog, and "Tyrannosaurus Wrecks", (2020) a T-Rex skull is stolen. 