Most people don't understand mantis are safe with corals. Most people assume when they say not reefr safe corals are out of the question. Corals just have to be put in securly so they aren't moved. People have beautiful mantis shrimp tanks with corals. Spearer's are better with inverts than smashers so some larger crabs and such may be safe with them. While smashers destory them but fast fish are better suited for them.