Aquarium Livestock Pet Care Guides

Blue Ring Octopus


Temperate Waters of Southern Australia

Average Size

1-3 inches


1-3 years


Blue Ring Octopi are primarily carnivorous (meat eaters) Crabs and bivalves (mussels) are this species main diet Frozen krill, shrimp, mussels. Unlike most other octopus, blue rings usually feed during the day.


Blue Ring Octopi are naturally shy creatures that spend much of their time hiding in rock crevices. While resting the octopus is yellow to brown in color. The blue rings are usually only visible when the octopus feels threatened.

The most important fact about the Blue Ring Octopus is that its bite is EXTREMELY VENOMOUS. This animal should never be touched. It's bite is painless, but it can easily bite through even thick rubber gloves. The poison is not injected, it is contained in the animal's saliva. This poison contains a neuromuscular toxin, which means that it causes paralysis, and eventually respiratory failure. THERE IS NO KNOWN ANTIDOTE Symptoms of a Blue Ring Octopus bite are; Onset of nausea, hazy vision (eventually leading to complete blindness), loss of sense of touch, speech, and ability to swallow. Within 3 minutes paralysis sets in and your body goes into respiratory arrest. Though not always fatal, mechanical respiration, and/or heart massage is required until the venom eventually works out of the system. With that said, you should NEVER even put your hand in the tank with this animal.

Tank Environment

Tank Size: Minimum 15 gallons
pH Range: 8.0 to 8.3
Temperature: 75 to 80 degrees

For Octopi, the tank must be escape proof. (READ: WELDED SHUT) Octopi are quite capable of escaping through even the smallest holes. Cover filter intakes with fine mesh bags (whisper bio bags work well) and secure loose lids with duct tape and/or heavy weights. It may not be pretty but it is absolutely necessary. Provide lots of cover with rocks/caves, terra cotta pots, pvc tubes, jars or shells.

Good water quality is required, with emphasis on oxygenation. Octopi are very sensitive to low dissolved oxygen concentrations. The water does not need to be blasting around but it should be noticeably circulating. Substrate should be small and not sharp.
Avoid undergravel filters, Octopi can slip under the grates. This is not harmful but will greatly reduce the already low visibility of your pet.

Lighting should be minimal, these creatures become stressed in bright environments.

Tank Mates

Octopi are solitary and best kept alone.

Did You Know?

  • Blue Ring Octopi have 2 venom glands, one contains a toxin that is used for immobilizing prey and is relatively harmless to humans, while the second gland serves as defense against predators and contains the poison that is deadly. Each of these glands are the same size as the blue ring's brain.
  • Blue Ring Octopi only have a life span of about 1.5 to 2 years and only get about as big as a golf ball.