Purpose <p>Underwater robots are required for underwater inspections due to industrial or environmental awareness demands. Bio-inspired fish-like robots can fulfill this demand due to their versatility and energy efficiency. These robots may present body/caudal fin (BCF) or median/paired fin (MPF) based locomotion patterns. Both locomotion patterns have been extensively explored, but currently, novel actuation strategies are under investigation. This work assesses the propulsion capabilities of a tail actuated by Macro-Fiber Composite (MFC) pairs for generating BCF locomotion patterns.</p> Methods <p>Firstly, experimental and numerical results are used to derive and validate an analytical model. This model is based on the Euler–Bernoulli beam theory, considering the electro-mechanical coupling of the MFC actuator pairs. Secondly, this model is used to derive the generated mean thrust using Lighthill’s analogy. Finally, an experimental campaign is carried out to assess the actual mean thrust provided by the MFC-actuated propulsion system.</p> Results <p>The experimental and numerical results demonstrated that a higher thrust force can be achieved by exciting the system at its second resonance frequency. These results are in line with Lighthill’s best locomotion solutions.</p> Conclusion <p>In this way, an MFC-actuated tail-like flexible beam should be excited at its second vibrating mode to improve its propulsion capabilities.</p>