Chabo is a young boy from Gosa Village.

He wanted to kill Arlong to avenge his father's death; Nami paid him and told him to leave. He later attacked Usopp, thinking that Usopp was a fish-man (due to Usopp's long nose), but Nojiko stopped him. After returning to Nojiko's home, she told him not to throw his life away, she then asks if he has a mother to which he answers "yes". He was then sent on his way to her because she was most likely worried about him.

Later the surviving Gosa residents called the Marines to help, the Marines arrived and Chabo announced to Nojiko and the Cocoyashi villagers what happened. The Marines fought Arlong, but it is all in vain. After the Fall of Arlong Park, he decides to forget about avenging his father himself and celebrates with the rest of Cocoyashi Village.

Source: http://onepiece.wikia.com/wiki/Chabo