Ive had my O. cyanea (Neptune) for about 3 months now. I keep him in a 125 gallon aquarium. I have trained him to open jars and tupperware containers but I cant help but feel that he is bored. I was wondering what people have put in their tanks to let their octopuses play with. I have been thinking about tying something positively buoyant to the rocks to see if it would interest him. I have also thought of getting one of those bubbling chests, Ive heard bubbling is bad for octos, but the air flow would be minimal. Does anyone have any other ideas?