my golden puffer and my porcy leave the crabs alone but i tried adding a urchin to my tank and it was ok for about a week, until my golden eye-balled it and it started picking at the purple urchins spikes until they were gone, then the urchin was lunch.
They leave the crabs alone, kinda strange? but they leave the crabs alone and i can have a cleanup crew, so i aint complaining!