I got my crayfish a little set of pipes to hide in. He’s a dwarf like yours. He lives UNDER the pipes in this little tiny space w a cherry shrimp! 🤭 So yes they can be friends. The only aggression I have seen mine show is he will occasionally lift his claw above his head and slowly open and close his pincher if a fish comes too close. It’s so cute! Mine rarely comes out from under his pipes though. I got him about a month ago and didn’t notice until I got him home that he was missing one of his pinchers and all but one leg on the same side 😫 I think maybe that’s why he’s staying hidden…hopefully once he molts he will come out more often!
Zroach121 
I got my crayfish a little set of pipes to hide in. He’s a dwarf like yours. He lives UNDER the pipes in this little tiny space w a cherry shrimp! 🤭 So yes they can be friends. The only aggression I have seen mine show is he will occasionally lift his claw above his head and slowly open and close his pincher if a fish comes too close. It’s so cute! Mine rarely comes out from under his pipes though. I got him about a month ago and didn’t notice until I got him home that he was missing one of his pinchers and all but one leg on the same side 😫 I think maybe that’s why he’s staying hidden…hopefully once he molts he will come out more often!