so i had this monster of a crayfish that was attacking everything it even tried to attack my common wolf fish with the wolf fish running away everytime. it attacked my wifes angel so i moved it then it killed my new jaguar cichlid when i moved it to my cichlid tank. it was doing a great job keeping my substrate clean i had 2 then it cannibalized the other one and went down hill from there this crayfish was about 3.5" and my jag was about the same size.
Crayfish can do some damage especially in a tight space. It is usually in defense like being picked at or backed in a corner. Most of the time they just wanna be left alone to scavange. "T"