i have a brittle star in my aggressive setup. he hasnt been bothered at all. he even gets out from time to time. my tank mates are as follows: porcupine puffer, panther grouper, violation lion, fox face, snowflake eel, purple tang, sailfin tang, cinnamon clown, koran angel, and domino damsel. all of my fish are pretty small but still no aggression towards my star. i also have tons of other lil stars in my tank. good luck.