Keeping an Octopus in a Home Saltwater Aquarium.

Updated 5/16/13



I have kept o. rubescens (pictured), brown, and even poisonous blue ring octopi, however I generally do not recommend Blue Ring Octopii (which I will go into further later in this article).

In fact a brown A. aculeatus was one of my first saltwater “creatures” back in the mid 1970s. They make great pets and are highly intelligent.
My pet octopus would recognize me and come to the top and stick its tentacles out to take food directly from me.

Here are a few points to keep in mind though:

*An Octopus will squirt ink when frightened, but that is rare.
Try and keep a peaceful environment and this will not become a problem.



*The Blue Ring Octopus (Hapalochlaena lunulata & Hapalochlaena maculosa which is more common and smaller; 5 inches- 1 oz.) from the Great Barrier Reef of Australia is are among the most toxic animals on earth with its neurotoxin (Tetrodotoxin).

A bite can kill in under an hour (although they very rarely bite).
Their bites are very small and often painless.
The Tetrodotoxin poison found in the Blue Ring Octopus can result in the victim being fully aware of their surroundings but unable to breathe. Because of the paralysis that occurs the victim has no way of signaling for help or any way of indicating distress. Respiratory support until medical assistance arrives may mean the difference between death and recovery.
Being bitten while alone is often a death sentence (See Blue Ring Octopus Bite).

To prevent a rare, but potentially lethal bite, wearing thick rubbers gloves should be adequate protection for the small beak on the Blue ring Octopus.

This said, as I already noted bites are rare. In fact these are very inquisitive animals and with simple cautions such as rubber gloves and a child proof aquarium, these can make an interesting pet that will thrive more easily in the common warm water marine aquarium than most brown octopii.
I would compare a Blue Ring Octopus personality to that of a friendly, neutered male cat I have; he is very playful and curious, but every once in while he gets carried away and over aggressive in his play. With this in mind I find Blue Ring Octopii this way, so protect yourself accordingly.

*These Octopus prefer the warmer waters that most home aquariums provide and generally the Blue Ring Octopus thrives much better than the Brown Octopus; however the poison problem in my opinion often over rides this “plus” (even though I have kept them).



Here are some important points for success in keeping a Brown & Blue Ring Octopus vulgaris and bimaculoides:

*Most Brown Octopus that are commonly available are cold water preferring so an aquarium under 75 F is best (under 70 F is better).
However the Blue ring prefers warm tropical waters above 75F.

*They need crab or other crustaceans in their diet. Keep in mind that they will consume cleaner shrimp, coral banded shrimp and similar aquarium tank mates.

*They are sensitive to nitrates above 20 ppm. So good filtration (such as the Berlin Method which may include live rock, deep sand bed, refugium, etc.).
A Protein skimmer is recommended, but I have successfully kept Octopi without a Protein skimmer.

Whether you use a Protein Skimmer or not, the key is low nitrates and a healthy environment (which includes Redox Potential, which a UV Sterilizer can help maintain).

Please reference this very in depth article that is a MUST READ for anyone interested in moving from basic aquarium keeping to more advanced aquarium keeping:


Back to Nitrates, besides the many methods for nitrate removal, the keeper of any Octopus should consider the use of a Reverse Osmosis Filter to provide nitrate free water for both “topping off” for evaporation or mixing new saltwater for water changes. Most tap or well water has at least some nitrates, so with nitrate sensitive Octopus, this is highly recommended piece of equipment to own.
Other methods for nitrate removal include the use of anaerobic filter media in filters such as SeaChem Matrix or chemical adsorbents such as SeaChem Purigen

*They have short life spans, often less than two years, and a warm aquarium will shorten this further (except for tropical Blue Ring Octopii).
Octopii further shorten their life by easily escaping from loose fitting tops.

*They do NOT mix with eels (mortal enemies)

For further reading about Octopus intelligence, please read this article from the Washington Post:
Brilliant Houdinis of the Deep

Other Recommended Reference Sites

-A useful source for current Aquarium Information and Resources (Pond too). Basic and in depth articles from Aquarium Lighting, Filtration, Filter Troubleshooting, Fish Nutrition, Aquarium or Pond UV Sterilizer Use, Ich, Pond Care, Nitrogen Cycle, and much more. Well researched and up to date aquarium and pond articles, answers, help, and links. Based on 33 years Professional experience & research in Los Angeles and now in Oregon. This Aquarium and Pond Information resource is a must read for any aquarist serious about current aquatic information and articles

For a friendly, Knowledgeable, aquarium forum with in a family atmosphere, Aquarium Forum; Everything Aquatic & Board is an excellent place to go for information, help or simply to share your love of the aquarium and pond hobby and help others. A superior place for information over such places as Yahoo Answers

FISH AS PETS; Articles and commentary of Interest to the Aquarium Hobby; Such as Parasite Retailers, Aquarium Planaria & Detritus Worms, Melafix Fish Dangers, & Celestial Pearl Danio, Galaxy Rasboras

Labels: A aculeatus, Aquarium Octopus, blue ring, brown octopus, neurotoxin, Octopus as pets