I am thinking of adding a dwarf crayfish to my 29 gal tank who has in it: 1 dwarf gourami, 8 black skirt tetras and 4 guppies. I am concerned that the crayfish will harass my fish, especially the gourami since he likes to hide in the caves and on the bottom where the crayfish would be. Would this be an issue? Should in consider amano shrimp instead? I had a bad experience with the guppies eating my ghost shrimp with my first shrimp attempt. Would a crab be a better choice? If so, what crab?