Oscar is a professional tongue-scrubber at the Whale Wash. He was inspired to do this job by his dad, but he eventually grew sick of it and he wanted to be somebody more important. Oscar's love interest was Angie, but for a long time, he didn't realize how he felt about her and he selfishly put fame and fortune before her. Things go bad for Oscar when his fame and fortune go down the undersea drain when Lino seeks revenge for Frankie's death at the hands of the "Sharkslayer". nearly gets killed by Lino, but then he reveals that it was really an anchor that killed Frankie. Don Lino is cool with Oscar and promises that the reef Oscar lives on is now safe from all sharks. Oscar becomes co-manager of the Whale Wash, and he and Angie get back together and become boyfriend and girlfriend.
Oscar reappears in the short, dancing with Angie at the Whale Wash in a parody of Saturday Night Fever.
Oscar would prefer to run away from danger rather than fight it, but he's actually very caring and will do anything to protect his friends from danger. He also admits that he was a nobody until he lied about killing Frankie and he does the same thing when he confesses that he's not a real sharkslayer.
In Shark Tale, he had no qualms about lying in order to make himself appear more heroic and powerful than he actually was. Oscar liked to think of himself as a ladies man, but he was somewhat awkward around females, accidentally bumping into a pillar when trying to seduce Lola and stuttering when he tried to tell Angie how he felt about her.
Oscar quickly became close friends with Lenny and he was romantically interested in Lola, but he eventually realized that she was shallow, vain, vengeful, and selfish. Instead, he fell in love with Angie. He also manages to make peace with Lino after admitting that he wasn't a sharkslayer, thus saving the reef from Lino and his sharks.