Fish finder help

[mick2me]

Hey Guys,

I'm looking to get a fish finder for my tinnie,

Someone has offered me a Garmin 160c colour fish finder for $120

when I googled it I found that it's a freshwater finder,

so I guess my question's are:

1. What is the difference between fresh and salt water fish finders?

2. Can you still use a fresh water finder in salt water?

Thanks guys,

Mick

P.S Also if you know of someone local to Vicky Point with a fishfinder for sale, please let me know, thanks.