ya sometimes those hairy crabs will eat up acro crabs and live in the acro. i ususally take the entire acro out and use toothpick to flick them out HAHA
or release new fishes at midnight when lights all off. tht trick usually works for me. but its not a foolproof plan ya? it reduces initial aggression and ensures the new lfs stabilises in the tank first, gives it a higher chance of surviviing
oh and fish channel still has a few cute kole yellow eye tang and 1 mystery wrasse, scribble and blue line angels all pretty well conditioned! boss is super friendly too!