My big fat zombie goldfish

When Tom's big brother decides to become an evil scientist, he dunks Frankie the goldfish into toxic green gunk, but Tom zaps the dead goldfish with a battery bringing him back to life as a big fat zombie goldfish who is out for revenge. Told in two separate stories, Tom's big brother becomes an evil scientist and his first experiment is on Tom's goldfish Frankie. To save Frankie, Tom zaps him with a battery to bring him back to life, but something is not quite right. Book #1