Different types of gunboats were used, some were heavier, equipped with the turrets of tanks, some were lighter and faster like pic #1 and #2.
The boats were used in reconnaissance, reconnaissance by force, mine laying and sweeping, and air defense.
Pic #3 Because the lack of water surface some boats patrolled on roads and rails. These two mine layers deployed anti-tank mines.
Pic #4 From Italy we got back many torpedoes of the late Monarchy. They were also used in anti-tank roles. In the picture a battery is ready to take out a T-34 approaching in the corn field.