2 ideas can make your fish echoes a little more "prominent" ...

Turn on the wider 83kHz beam so the target gets "pinged" more repetitive times ...

And/or ...

Increase the 2d Chart Speed to "stretch" the displayed echoes out more across the screen scroll ...
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There is good detail in your SI image ... It just needs a little brightness by increasing the SI Sensitivity some ...

I keep the SI Enhance menu open anytime I'm viewing SI ...

This gives me instant access to the SI Sensitivity setting to brighten/darken the SI image ...

(Remember to slow the Chart Speed back down to equal boat speed when not viewing the 2d idea from above) ...

Rickie