I have decided to get a pontoon boat to fish out of this summer, the small single person pontoons, and I am going to put a fish finder no it. What kind of battery do they use? Do I need to get a marine deep cycle or will any battery work. I am usually not on the water for more than 3-4 hours at a time.

what other accessories will be battery?  lights, livewell?  

As of now, nothing other than the fish finder.  Down the line I may get a TM, and that will need a deep cycle battery, but for now just the fish finder.  I am probably going to get an Eagle Cuda since they are small and inexpensive for the quality.

See if you can find one of the "portable" units.  They come with a base that holds D cells. You just plug in the transducer and you're all set.

I would recomend one of these batteries and one of these to charge it

charger

Paul