I will eventually add fish in a couple months...it is something that people say dont do and I might get blasted, but again I know somebody who has kept mantis for many years and has always kept fish with them. He said first you want to establish a feeding routine with the shrimp....that is why you want to wait a couple months. When you first get them, they will grab whatever they can because they dont "know" when their next meal is coming. But by establishing a regular feeding schedule it will decrease the drive...a fed shrimp will not go after a fish, to much work. He oversimplified the whole thing for me...but it is the basic concept.
I also am working on never dropping the food in the tank. When I feed krill or silversides I use a feeding stick and hold it down to him. IMHO dropping it in would stimulate a fish swimming to him, being on a stick, you are giving it to him. Same when I give him a crab or snail..he sees me drop it in the tank...hence he associates me with supplying his food.
Of course, you dont ever want to feed a fish to them if you are planning on keeping fish in there. Also dont want to keep any fish that are bottom dwellers or slow moving fish...I wouldnt keep anything like a clown goby or a sandsifter...way to tempting! Plus I am not going to buy anything expensive, because you never know when Bob will break the rules...even though my friend has kept many of mantis with fish and never lost a fish, Bob may not have read the same MANTIS BY-LAWS!
I think somebody on here has fish with their mantis...I cant remember who a firefish...I think I am going to go with the obnoxious damsels!