I created robotic fish prototype that models a carrangiform type fish (you can think of it as similar to a shark) for a class at MIT from 10/21/2018 – 12/6/2018.
I designed a skeleton structure for my fishbot based on parts from ServoCity.com. I decided to give my fish with a waterproof servo train, and had the three servos in the train perform phase shifted sinusoidal periodic rotations. This caused an undulation type of effect. I also glued styrofoam to the fish to allow it to float and put a tail fin on the end of the fish to help with forward propulsion.