[CA] [CA11] another question about fish finders, transducers

[cheesecake32]

I have been reading the discussions here in hope of finding the answers but since I have no clue what I am dealing with I have given up and am asking directly.
my wife decided we needed a sail boat and bought a 32 foot Bavaria (hence the "cheesecake" user name" ). it is kitted out with raymarine goodies, many of them up graded 12 months ago. I am not big on sailing but I do enjoy feeding fish and would like to be able to see if the is anything under the boat worth feeding. I have snooped around a bit and as far as I can tell it has a
-p319 transducer and a ST800-P120 both through hull.
-C80 multi display unit
but there is no DSM connected to the display.
is it possible to set up a fish finder with the equipment I have by adding a DSM (250 or 300)

I have attached pictures of the tags.
thanks in advance for any help.
kind regards, cheesecake.

ok, so I got to "insert into post" with the attachments and it wouldn't go any further so here is the info as it stands on the tags
AIRMAR. 11/08
P319
50/200kHz-A
PN:31-641-1-01
customer part #
RUL -31-641-1-01

AIRMAR. 12/08
PN:31-487-1-02
customer part #:
RUL-31-250-4-42