The ability to navigate, hunt, and communicate by electric current in water most likely make up for the effect of dark, murky water on which sense?

The ability to navigate, hunt, and communicate by electric current in water most likely helps make up for the effect of vision. The answer to your question is VISION. 

If fish live in a dark, murky water, that means that their sense of vision is affected. In dark, murky water they could not see anything. So, fish that lives in this kind of water developed the ability to o navigate, hunt, and communicate by electric current in water. This ability is known as electroreception. Among fish, electroreception is present in some sharks and rays, and electric eels.

I hope that this is the answer that you were looking for and it has helped you.

The speed was not exceeded so it was slow