There are several reasons your water cooler might smell a bit fishy. One possibility is that bacteria may have grown on the surface of the water container, especially if it has not been properly cleaned and sanitized according to the manufacturer’s instructions.
Another potential cause could be mold or mildew growing in the coils at the back of the unit or in other inner parts that are difficult for you to access.
Other factors, such as changes in temperature or humidity levels, can also contribute to bad odors in your cooler. To determine what is causing the smell and eliminate it from your unit once and for all, you may need to consult a professional specializing in water coolers.