The Amphibian = The Amphibian Man

Alexander Belyaev (1884-1942) is one of the founders of Russian science fiction literature and the first of the Soviet writers to devote himself entirely to this genre. In all, he has written more than 70 science fiction works, including 17... novels. For a significant contribution to Russian fiction and his visionary ideas, Belyaev is often called the "Russian Jules Verne."
The Amphibian is a science fiction novel written in 1927 and first published in 1928.
Fishermen and pirates of Buenos Aires are frightened - a mysterious "sea devil" appeared in the sea. However, a cold-blooded businessman Pedro Zurita, the owner of the crew of pearl-divers, decides to catch the mysterious creature and adapt it to his business. This creature with both lungs and gills of a shark is actually a young man named Ichthyander, the result of Doctor Salvator's bold experiments with organ transplantation. One day, Ichthyander rescues a girl drowning in the sea - Gutierrez, the adoptive daughter of Baltasar, one of Zurita's assistants...