I had a ~2 in blue cray with similar stock. He did kill my pleco but that was it and nothing messed with him. I also have one in a 29 gallon with a few tiger barbs and danios and he does not really mess with any of the fish either. Lots or hiding spaces wil help it survive molts. Good luck
In a tank that size they should be able to coexist, as long as there is adequate hiding for the cray. My Tangerine Cray just sits under a rock in his 10g most of the time anyway, and theres not even any fish in the tank.
I too have a crayfish with Tiger Barbs and Danios, and 1 Platy, it recently molted and lost a bunch of legs (Tiger Barbs can be brutal) other that that I have a rather large crayfish that recently met it's maker thanks to the cat.
Had another that went for a walk...didn't end well. Found him under the fridge cooking.
I pulled them from a local stream...I see them selling the same ones at the LFS.
Crayfish in a tank with fish generally ends badly one way or another, I've had them live fine for a year or so and then in one night you end up with massacre......