I'm just asking about the sponges because my lfs told me that some of them, when they die, will nuke an aquarium, and is the reason why sponge eating nudibranch are toxic...I also had a mass extinction in a tank with two condy anems involved, and my lfs blamed dead sponges and cucumbers in the rock. I was more thinking about the idea of the pipefish shoving it's head into a pore and the sponge.. being non-photo, closing on it. As far as out competing for food, I have 2 scooter dragonets (recused both of them starving at petco.. I asked the employee what they ate and they had no idea..) and they are both eating frozen mysis, I guess that wouldn't matter as they still will be scooting searching for pods...