What dwarf cray do you have, from what I know least cray is the only safe option for shrimp tank, and Mexican dwarf cray is notoriously aggressive towards their tank mate I seen them hunt guppies at night, brazo is ok they’re usually friendly and social like least cray often travels in groups of 3 cray just like least cray but they’re little larger.
I have my least cray for about two months now with no issues, I also kept them before that also no issues but I noticed they hunt snail a lot especially at night but also day time.
BitchBass 
What dwarf cray do you have, from what I know least cray is the only safe option for shrimp tank, and Mexican dwarf cray is notoriously aggressive towards their tank mate I seen them hunt guppies at night, brazo is ok they’re usually friendly and social like least cray often travels in groups of 3 cray just like least cray but they’re little larger.
I have my least cray for about two months now with no issues, I also kept them before that also no issues but I noticed they hunt snail a lot especially at night but also day time.
I didn’t wanna post a video of the hunting part…the [shrimp tanks with the T-bridge are behind this one](https://www.reddit.com/r/shrimptank/comments/180y3q9/triple_shrimp_tank_with_tconnection_bridge_diy_we/).