Garmin Fish Symbols

I have a Garmin 531 GPS/Fish Finder. It has the option of turning fish symbols on or off. I think what it shows as fish symbols is not always fish or small fish that there is no need to waste time on. My fishing buddy says leave them on because in makes it easier to read. I need the opinions of people with more knowledge on the subject than my friend and I. Turn them on or off and why?
Thanks in advance for your inputs.

All brands that have fish symbols produce false signals at times. I personally turn mine off. You get used to how fish, baitfish, and clutter look on the screen.

SE Kansas grass grower