A portable and easy-to-use alternate fish cutter is provided. It includes a housing constituting a handle, a cutting knife, a driving mechanism, a switch button, and a power supply module. The cutting knife includes a pair of left and right knives arranged side by side. It also includes left and right knife arms. It also includes a worm wheel arranged behind the left knife arm and the right knife arm. It also includes a left connecting rod and a right connecting rod. It also includes a worm and a motor for driving the worm wheel to rotate. Surfaces of the worm wheel and the worm are both provided with mutually meshing helical teeth. The structure of the invention is small and portable, fits the shape of traditional knives, can improve the efficiency and experience of slaughtering.