As part of our research on Hapalochlaena behavior and toxicity, we have kept hundreds of individuals. Here are a few points to consider.
1. They are not particularly hardy. Most arrive from the collectors as adults and live only at most a couple of months.
2. Behaviorally, they aren't that interesting except with respect to reproduction. Most individuals spend their time sitting on the wall of the aquarium. This makes them visible, but rather boring.
3. They will crawl out of the water and escape their aquarium unless extreme precautions are taken. We use two types of containment. For large individuals or for observations of behavioral interactions, we use all glass aquaria plumbed with sealed intake and output pipes that connect directly to a canister filter. The all glass lid fits flush and is weighted down with heavy (at least 5 lb) weights. This restricts air circulation, but since we generally keep only one or at most two individual per tank, oxygen is not a problem. With all glass tanks and lids there are no blind spots. This is important. We can always visually locate the animal before opening the tank.
When we have smaller individuals, or a large shipment, we temporarily house animals in gallon plastic jars with hundreds of small (1/8 inch) holes drilled in the sides and top. These are escape proof. Several jars can be kept submerged in a 100 gal aquarium with strong water circulation. The jars contain a heavy pvc tube to weight them down and provide a refuge for the octopus. When opening the jars to feed or clean them, the jar is removed from the tank and placed in a plastic tube so that the water drains at least half way. The jar is not opened until the octopus retreats to the bottom below the water line and is clearly visible.
4. Access to the aquarium room containing blue-rings is locked and restricted to individuals who have been fully briefed and trained in the dangers that blue-rings pose and how to deal with them.
5. No one is allowed to open a blue-ring aquarium or jar unless there is another individual present who is trained on what to do should one escape and/or bite someone. (In the case of a bite, call 911, inform the paramedics the danger posed by blue-rings and that the toxin is TTX, and start Rescue Breathing should the victim have difficulty breathing.) Every room and aquarium containing a blue-ring is clearly labelled with a sign identifying the occupant, warning of the danger, and instructing what to do if bitten.
6. Blue-rings are never handled (even when dead) without proper gloves and we always use nets and feeding sticks, not our hands.
Fortunately, in over 20 years of working with blue-rings, we have not had any envenomations although there have been a couple of escapes when a lid was left open just a crack.
The precautions we take in the lab may not all be feasible in the home, particularly controlling access, and I do not recommend keeping blue-rings in the home aquarium. In my laboratory I can control access to these animals, but in the home how do you keep a curious 8 year old from reaching into an aquarium to pet the pretty octopus?
Roy
