You might have to play with the settings, color palette, and zoom features to "see" fish images. And like CatFan says, you will have to be moving to get clear images on the screen. I have the Elite 5 DSI and can get decent images at 0.3mph. Clearer/sharper images occur at speeds greater than 0.5mph. My tdx is mounted on the trolling motor, and ~2mph is my top speed.

It should work OK in 10' of water ... but the swath of bottom coverage will be something like this, depending on whether you have the 455kHz or 800kHz beam chosen :



As you can see by the chart ... at 10' your 455 setting is about 1.5 times the depth of water & the 800 setting is about equal to the depth of water. That means the fan shaped sonar beam is showing a bottom path of about 5' to either side of the transducer when using 800kHz ... and about 7' to either side when using 455kHz.

If you were using conventional 2d broadband sonar ... in 10' of water your 20deg cone would only be showing a circle of about 3' wide. You'd have to have 60deg cone angle capabilities to get a circle 10' wide in 10' of water. And your images would be "blobs" rather than picture images.

... cp