The members of the mutant group Helix believe that Carcharo's mother and aunt were born in Mexico and went to the US where each one married. When the two sisters were both pregnant, they were given mutagenic drugs by the gynecologist Dr. Love. Carcharo's mother was then deported to Mexico, and her sister went with her. There Carcharo was born on the same day his mother's sister gave birth to a normal looking baby, Yolanda Montez, who later became Wildcat II.
However, Carcharo was born with features that resembled a human shark. Apalled, his mother tried to drown both herself and her newborn son, only succeeding in killing herself. Her husband then committed suicide, too. However, due to his gills, the baby Carcharo survived. Apparently, he went on to grow up underwater without human supervision. How he came into contact with humans and learned to speak was never explained.
Carcharo first encountered Yolanda when she was working with the members of Infinity Inc. The team were investigating shark sightings off San Pedro,California. These gigantic sharks were controlled by Carcharo and he then captured Wildcat and took her to his enormous submarine. Carcharo and his two female companions, Rema and Mora, took Yolanda along to their meeting with the other members of Helix. The other members of Infinity Inc then arrived, saved Yolanda and captured Helix's leader, Mr. Bones.
Carcharo then tried to take control of Helix and become the new leader of the group. Bones, freed from prison, battled Carcharo, and impaled him with a piece of metal. Succumbing to his wounds and the effects of Mr Bones' cyanide skin, Carcharo bit off most of Bones' left leg before he died.