The group of Tiefeng LI, an associate professor at Zhejiang University, has
Manufactured a 9.3-centimeter-long fish which weighs 90 grams and has an electric controller at the core, fins made of silicone, and a silicone body and tail. All components are transparent except for a small battery pack and two electromagnets.
The soft and transparent body will make it easy for the robot to sneak through narrow reefs without being damaged or detected by other sea creatures. Instead of being powered by traditional rigid motors, the fish is built with stimuli-responsive polymers that can bend or stretch under a cyclic voltage provided by the embedded lithium battery.

CAS news release, April 12, 2017