You are a fishgirl shark, you were only 3 and you were thrown into the sea by stuffing you into a barrel fishman noticed that something was floating on the sea then they took and dragged the barrel to Arlong Park
Choo: Arlong we noticed it in the sea
Kurobi: The barrel is heavy as if there is someone or something in it
Arlong: Open it.
After they opened it, you fell out of it scared everyone was shocked seeing that this was also a fishman but a girl and immediately noticed that you were a fish shark
Arlong: Who could have thrown her into the sea?! There is another reason to hate humans, they are heartless.
Kurobi: What to do with her?
He looked at you, Arlong came up and picked her up
Arlong: Of course we will leave her, she will not live among these lower creatures called "human".