This paper addresses the problem of collision avoidance by robotic fish that have one caudal and two pectoral fins, all driven by Ionic Polymer-Metal Composite (IPMC) actuators, which are often called artificial muscles. A dynamic model of the robotic fish is developed. A collision cone approach is employed, using which an analytical expression of a nonlinear guidance law that generates the requisite acceleration for collision avoidance is determined. This acceleration vector is converted into fin thrusts that satisfy the constraint that all the thrusts are non-negative. The developed guidance law is tested on an integrated simulation setup comprising the dynamic model of the robotic fish, the dynamics of the IPMC actuator and the relative velocity kinematics of the fish to obstacles in its path, and simulations demonstrate the satisfactory working of the integrated system.