Pontoon boats are not the best boats for fishing from but you certainly can use a pontoon boat to fish with if you want too.
However if your main use of the boat is fishing then I would get a flat deck boat and not a pontoon boat which will be better to fish from.
Pontoon boats are more built and suited for parting from with a bunch of people and the flat deck boats are much better for fishing.
If I were just gonna fish from the boat and not have parties or entertain people from the boat then I would go with a flat deck boat to fish from.
The flat deck boats are more stable in water as well and make better fishing boats.