I saw ghasts in 3x3 areas in Nether fortresses. Sorry that i didn't take a SS. If happens again i'll take one.
Mobs in Nether spawn in incorrect locations
Ghasts don't make sounds
Wither Skeletons and Blazes Do Not Spawn Again in Nether Fortresses
Ghasts in the nether are impossible
Nether mobs spawn in unusual places