The Son of the Shark (1993)

Brothers Martin and Simon, not yet teens, are incorrigible vandals; Martin runs away from reform school, Simon from foster homes, and they always find each other in a seacoast town of Lignan, where their destructive behavior is infamous. (It may date to their mother's leaving the family.) Martin is philosophical, romantic, and poetic: he dreams of being the son of a shark; he holds tight to a book about goldfish his mother gave him. In both halting and wild ways, he tries to court Marie, a neighbor girl. Simon, with a pocketknife and an intractable will, seems more dangerous to others. What, on earth, is there for these children-becoming-men? - IMDb