Ever shot fish in a barrel?
It’s not as easy as you think.
Fish are small moving targets.
And you have to take into consideration the refractive properties of the water.
Light bends considerably depending on the angle you’re looking into the water.
Don’t believe me? Stick a straw in a glass at an angle and look at it.
That weird break in the angle is due to refraction.
So, go ahead. Try to shoot fish in a barrel.
You’re better off just pouring the barrel out, picking up the fish, and smacking them on the ground until they’re dead.