This work presents the performance of the plain swimming motion algorithm used in the design of a robotic fish based on Mackerel (Scomber scombrus) which belong to the Teleost species of fishes. The wriggling motion patterns were built into the robot firmware. The robot tail is a six segments plywood panels with vulcanized rubber acting as joints. This tail structure is driven by three remote-control servomotors (Futaba 3003) and that are controlled by a single PIC18F4520 microcontroller. The microcontroller which is the heart of the robot firmware, use the built-in algorithm to determine the sequence of the operation of those three servomotors in a way that they are all simultaneously out of phase at any given instance, thus creating a traveling wave that propels the robot forward. Experimental results based on the algorithm shows that the robot was able to achieve a maximum linear speed of 8.26 cm/s (0.21 body length per second) while the tail was oscillating at a frequency of 1.15 Hz.