by Nancy King -- last updated 3/1/2004
Nancy is a member of the TONMO.com staff -- you can discuss cephalopods with her in our Octopus Care forum.
Keeping an octopus is fun and interesting, but an octopus is not the easiest pet to own. You need understand saltwater aquariums as well as how to take care of a ceph pet to be a successful octo owner. Here are some things to think about and to guide you before you take the plunge and buy an octopus.
1. Do you know what species you're getting?
Octopuses of different species that grow to widely different adult sizes are sold as pets, and tank requirements for these octopuses vary greatly. Also, the recommended water temperature is determined by the species. Octopus bimaculoides (bimac) seems to be the most popular pet octopus in the U.S. and is now often captive bred. It is diurnal (day active), not too large, and will interact with you.
If you intend to buy from a local fish store (LFS), be aware that the store may not know what species they are selling so you should try to ask some questions like "where did it come from?" and also find out under what conditions the octopus is being kept. Especially ask about the specific gravity, temperature and pH of the water. Be suspicious of names like 'common', 'brown', 'dwarf' and Bali octopuses as these terms rarely mean a thing. You sometimes never know if you are buying an adult dwarf with weeks to live or a baby that will grow into a huge octopus!
2. Are there species that should be avoided?
Avoid the temptation to buy a blue ring octopus! These are commonly seen for sale in shops and rarely do well in captivity. The shipping success rate is very small, many octopuses may have died just to get one alive and not least of all the octopus bite can kill you! Many species of Hapalochlaena only live for 6 months and is probably already an adult when you get it with maybe only weeks to live. Only the most experienced ceph keeper should attempt to keep a blue ring octopus.
3. Do you know what size tank you'll need?
The minimum tank size for a bimaculoides, one of the most popular octopuses sold as pets, is 50 gallons, and larger is better. O.vulgaris would require a much larger tank.
4. How will you choose the filtration, pumps and other equipment?
Refer to Colin's article, Ceph Care Equipment List - read it and look at the links. Remember that an octopus can produce nearly 3 times as much waste as a fish of a similar mass, so aim bigger than recommended for a fish-only or reef set up. A big protein skimmer is strongly recommended.
5. Have you already set up and cycled your tank?
You need a mature tank for your octopus. Three months of running is recommended for a ceph tank before adding an octopus or cuttlefish. Ideally run the tank with some fish like mollies or damsels but be aware that damsels will need to be removed before the octopus is added and any other fish will be seen as a snack! You can't just buy a new tank, add water and some live rock, and then plop in your octopus.
6. Do you understand that you can keep only one octopus per tank and that there are very few other creatures that can live with it?
A species tank is for one member of a species and no other animals. Most other aquatic creatures should not be kept with your octopus, including fish. What can be in the tank is a starfish or an urchin (pencil type, not type with pointed spines). Anemones should not be kept with an octopus, because they will sting. Cuttlefish and octopuses cannot be kept together.
Some attempts have been made to keep two octopuses together in a large tank, but the results so far are that one octopus will eventually kill and eat the other one.
7. Have you created a good environment in your tank - lots of hiding places and caves?
You can build caves with sturdy live rock, and you can also add PVC pipe for places to hide. Caves should be various sizes to accommodate your octopus as it grows. They also like to crawl through hidden passages in the rock and peer through holes. Some people are guilty of having a bare tank with a couple of rocks so they can see the octopus more but this generally has the opposite affect. The more caves and hiding places the better and the more likely you are to see normal octopus behavior!
8. Do you have a way to close your tank off so your octopus cannot escape?
An octopus can escape through a tiny hole, no larger than its beak. Many people are using duct take to seal their tank and prevent escape. Although bimacs are less prone to escape than some other species like O. vulgaris, they do occasionally get out. Pay particular attention to where pipes and wires enter the tank and don't forget to make the overflow secure if using a sump.
9. Are you able to keep you octopus at the desired temperature?
Bimacs can tolerate temperatures in the upper 70's, but this will shorten their lifespan. You need to find a way to lower the temperature to the lower 70's, such as using a fan or chiller on the sump. A tropical octopus can live at a higher temperature.
10. Have you found a source of RO/DI water or a way to make it?
RO/DI water is water filtered by reverse osmosis (RO) to demineralize it, and is further purified by a deionization (DI) process that removes contaminants. Use RO/DI water to make up the salt water for your tank. If you buy salt water from your LFS, make sure it's based on RO/DI water. Water quality is a major concern when keeping cephalopods. They are much more sensitive than fish as they lack scales to act like a barrier and have a huge surface area of skin.
11. Have you had your water in the tank tested for copper?
You need to make sure that the level of copper in your tank is zero. Copper is fatal to octopuses with no exceptions. Be wary of using any tank which has had a copper based treatment used in the past.
12. How will you carry out water tests?
Test kits and a hydrometer will enable you to find out about your salt concentration and make adjustments to conform to the recommended parameters. You need to test for specific gravity (salinity), pH, ammonia, nitrite, and nitrate. Your LFS will do these tests for you, but since testing must be done frequently, it's better to have the equipment and test kits at home. Ammonia is the most toxic and tests should be done on a regular basis, as octopuses are prone to making a lot of mess at feeding time.
13. Have you already located a source of shrimp and crabs for your octopus?
A young octopus will need smaller food such as small shrimp, hermit crabs, small fiddler crabs, small pieces of seafood, and even amphipods from the live rock. It may be able to eat snails and a few can even tackle small clams and mussels at a young age. Try pieces of fresh scallop for a treat. A diet of goldfish or other feeder fish is not recommended, as there have been many reports of early deaths. Artemia (brine shrimp) should be avoided for baby cephs as this is severely lacking in the protein.
14. What happens if I buy an older octopus?
Octopuses have short lifespans, often less than a year. Many people prefer to buy a young octopus so that they can have their pet longer. Of course, there is nothing wrong with buying an adult octopus and giving it a good home. Occasionally octopuses are bought as gravid female who lays eggs shortly after purchase. This is common in some species and success with the larvae varies. Generally speaking large egg species can be raised in the home but small egg species are very difficult to rear.
15. Have you thought about what impact on your life keeping an octopus will have?
Not only will it restrict vacations (octopuses are much more demanding than fish), but also you may find yourself making extra trips to the fishmarket for food and spending a fair amount of money on octopus food. You will have an easier time keeping your octopus if you think out these aspects in advance.
16. Have you researched and read as much as you can on the subject before buying an octopus?
Too many people buy on impulse and this causes many problems for them. Although there are no books on octopus keeping, there is a wealth of information here on TONMO.com (read the past Ceph Care postings and the articles) and on the links provided.
Before You Get An Octopus as a Pet...
Checklist: Things to Think About Before You Get An Octopus as a Pet