The engineering translation of the aquatic animal propulsion systems and its appropriate application to marine vehicles help them to achieve movement with less power and hence resulting in the CO2 emission reduction. In this paper, the design of a robotic fish with pectoral and caudal fins, which operates at subsurface, is considered. The robofish body shape and fin geometrical parameters are also important with regard to the resistance and power aspects. Numerical studies are conducted with the robotic fish to determine its resistance in the bare hull and also for the case fitted with fins. Experimental studies carried out on a remotely operated surface ship with thunniform mode of fish propulsion, which operates at subsurface, are considered. Model tests are performed to analyse the propulsive performance of fishtail propulsion for the remotely operated surface ship in bollard pull condition and in self-propulsion mode. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.