depth finder

[denniscobb796]

i am looking at buying a new depth finder. i have heard that with color depth finders it is possible to tell the difference between scaled and non-scaled fish. is this true? if so is this exclusive to certain manufactures and/or models?
i'm on a limited budget because i've already spent too much on rigging out my boat and buying equipment for the big blues!!! anyone with suggestions on a lower end but functional color depth finder (only)...i already have a gps.

thanks