by Colin Dunlop
One of the most common emails that I receive starts along the lines of, "I have seen an octopus for sale in a pet shop. What do I need to keep it properly?"
Here is a list of some information and equipment needed for an octopus aquarium with links to sites where the information is explained. (This is by no means a fully complete list but may be added to at a later date)
There is no easy and fast way to becoming an octopus keeper but by reading around the subject, checking out past posts on TONMO.com and by keeping hardier marine fish for a while; you will get there eventually!
It is important for first time marine invertebrate keepers to learn how to control the water parameters and familiarize yourself with the equipment. It is a tough lesson learnt that kills your octopus!
Some people have managed to set up an octopus aquarium with no prior knowledge of keeping marine invertebrates and have done well. However, that is the exception. Too many octopuses are bought on impulse and inevitably die through incorrect care. Please refrain from jumping in headfirst and set up the aquarium properly at least 3 months in advance.
What species of octopus do you want to buy? This can be a frustrating time because the vast majority of shops that sell octopuses have no idea of the species name! They are often called 'brown octopus', 'common octopus', 'Bali octopus' or even worse simply 'Octopus'. You need to know what species it is or at least what locality the octopus came from. That can make a big difference in its care requirement!
If you buy an unknown small octopus with a 1" mantle length it could be a baby that will grow to over 3 feet arms spread or perhaps it is a fully-grown adult dwarf with only days left to live???
Cephalopods do not naturally live long. A typical life span of an octopus is in the region of 6 months to 18 months. If that seems distressing then perhaps an octopus is not the pet for you. You will get attached to it! It is always better to try and find out how old your pet is before you buy it, the younger the better.
An octopus can be a very rewarding animal to care for but they are not for everyone. They require special conditions and feeding. Think carefully before you buy an octopus, they can end up costing you a lot of money!
Just because an animal is available for sale in an aquarium shop, does not mean it is suitable for the home aquarium! Please avoid dangerous species like the blue ring octopuses at all costs! Why? See this article by ceph expert Dr Roy Caldwell.
Other species that should not be kept include species that can get too big like the Giant Pacific Octopus or species, which could be under threat from over collecting like the Mimic or Wunderpus. See this article by TONMO.com member Chris Shaw and Dr Caldwell.
Feel free to ask subsequent questions on the Ceph Care category of the TONMO.com message board.
Thanks to Stan and Debbie Hauter of About.com's Saltwater Aquariums Page for allowing me to link to their products pages.
The minimum size tank for an octopus to live in depends on species. The most commonly sold octopus in the US, Octopus bimaculoides (bimac), needs a fairly large aquarium: 50 gallons is recommended as a minimum. The tank can be either all glass or acrylic.
A marine aquarium that is already up and running may be converted into an octopus aquarium providing that copper based medications have never been used to treat fish with diseases like 'ich' and that all of the fish are removed as they would quickly become octopus food or pester the octopus.
If starting from scratch the octopus aquarium needs to be cycled/matured for approximately 3 months before an octopus can be added. Please visit this link to learn more about setting up aquaria.
Set up the aquarium as if setting up for a mini-reef tank. And be patient for THREE MONTHS! An octopus aquarium requires a longer cycle period than a typical fish tank does because they are more sensitive to water quality.
The Octopus Aquarium's hood
Some species of octopus are escapologists. They will try and squeeze through the smallest of gaps and leave the aquarium. Many an octopus has been lost this way and in most cases if found dead on the carpet!
So, to prevent this an escape proof lid or hood has to be made for the octopus aquarium. One of the easiest ways to do that is by using glass covers between the tank and the hood, but be warned that a determined octopus can sometimes move these covers! Make sure that all tanks are covered with non-moving lids and that all pipes coming to and from filters or sumps are meshed off or use a sponge to allow flow but prevent an octopus climbing into one.
Some species are more prone to escaping than others, especially Octopus vulgaris and Octopus briareus. It is said that bimacs are not prone to climbing out of aquariums but I believe it is better safe than sorry.
The water used for an octopus aquarium is of paramount importance! The water that comes out of our taps is for our consumption, not for cephalopods. It is safe for us to drink but potentially poisonous for an octopus!
Chemicals are added to our drinking water by the water authorities. This may include chlorine, chloramines, fluorine etc. Also, run off from farmland can produce high levels of nitrate and phosphate in our water supplies; something we really want to avoid putting into our aquariums.
To achieve pure, safe water, aquarists contemplating keeping a cephalopod should consider buying a Reverse Osmosis unit. This removes all unwanted toxins, however; you may be lucky and have water that is acceptable for cephalopods. Make sure you have your tap water tested properly.
Some aquarium shops sell reverse osmosis water (ROW) by the barrel or bucket full. It may be worth asking them about it!
The best way to provide seawater for your octopus aquarium is to buy synthetic sea salt from your local fish shop. This salt is specially made for aquaculture and other salts we may use in daily life will not do.
Many modern fish keepers who have marine fish keep the level of salt at a concentration lower than real seawater. Marine fish can tolerate this and aquarists feel it prevents parasites. An octopus tank HAS TO BE KEPT AT FULL STRENGTH SEAWATER! They will not survive if the salinity is too low!
Click image to enlarge. A simple 'swing arm hydrometer' like this one can be bought from your local fish shop. It's an inexpensive and reliable way to check the salinity of an octopus tank's water. Aim for a reading between 1.023 and 1.026.
This topic is still up for debate in many circles as there are different ways to utilize the substrate of an aquarium with the filtration. Personally I prefer to keep the substrate as simple as a fine layer of aquarium sand. This is very easy to clean and does not become clogged with waste particles.
Do not use course coral sand that is often sold for home aquariums, as this can be quite abrasive on a cephalopod's skin. Fine sand works better to a depth of 1".
There are exceptions to this rule; some species of octopus require a deep sand bed to hide in otherwise they may perish. Again it is important to know exactly what species of octopus you are setting up your tank for!
NB Undergravel filtration will not work in an octopus aquarium. The octopus may disturb the filter by digging and may even figure out how to climb down the uplift tubes and live UNDER the undergravel filter!
This is perhaps the single most important aspect of the octopus aquarium. Think of it as being like a life support machine. If the filtration fails the octopus will die.
The main aspect of a filter relies on the nitrogen cycle; click here for more information.
The octopus can produce three times as much waste as a fish of a similar mass so the filtration of an octopus aquarium has to be three times over spec for a tank destined for fish only!
There are many different forms of filtration. Here are some links to follow on the different types suitable for octopus aquariums: sumps when setting up octopus aquariums. It is an ideal place to keep equipment like heaters and protein skimmers, etc.
Carbon should be used within all octopus aquariums as it adsorbs excess waste from the water than can often make aquarium water look yellow. It is especially important to ceph keepers as it absorbs any ink if an octopus ejects any.
No, not the kind of rock you may actually get blood out of but this term means that the rock has came from the sea, normally a coral reef and is encrusted with life forms like sponges and algae. More importantly, live rock houses bacteria that help to break down the pollutants in the nitrogen cycle that affects our tanks. Live rock can be used both as an aesthetically pleasing aquascaping medium and as an important part of the tank's filtration.
Click image to enlarge. This newly introduced piece of live rock already has signs of purple coralline algae growths. However, it is it's bacterial colonies that are of most interest to us.
This is another very important piece of an octo-aquarium. A protein skimmer removes wastes from the water before the filter even has to worry about it. I recommend that all closed system aquariums used for cephalopods run a skimmer on a 24-hour basis. They also come into their own when a cephalopod inks in the water! The skimmer, just like the filter should be over-spec. However, any skimmer is better than no skimmer...
Click image to enlarge. This picture shows a properly functioning protein skimmer in action. The dark brown liquid "gunk" in the collection cup is testament to that! Model shown is the Aqua Medic turboflotor 1000 multi.
To make sure that we are setting up the octopus aquarium properly we must use test kits to measure the water parameters. A fully set up and running aquarium should still have tests done on a regular basis to prevent unsatisfactory parameters from occurring. It really could be life or death for your cephalopod...
We are especially interested in keeping a close eye on pH, ammonia, nitrite, nitrate, phosphate, calcium, alkalinity, copper and oxygen.
Octopuses are a type of animal that would have a den or home in the wild. They require a place like this in captivity. This can be either made out of rocks or out of pipes. It is important to ensure that all things used are safe for aquarium use and that they are securely fastened to prevent falling and potentially injury to the octopus.
Personally, I have a typical octopus tank filled ¾ full with live rock. This provides ample hiding places for the octopus.
Many people give an octopus a scant home. That is an aquarium with a layer of sand and only one or two rocks to provide a hiding place. The theory being that they will see the octopus more because it has nowhere to hide. From experience, the more hiding places you offer, the more secure the octopus feels, and the more you see the octopus.
Depending on what species of octopus you eventually decide to keep, you may need a heater. This all depends on what parts of the world you come from... maybe you are lucky enough that you wont need a heater! The rest of us will have to use a combined heater and thermostat to keep the water at a constant level. Make sure that you buy a heater suitable for the size of your aquarium! And always use an accurate thermometer!
Perhaps you want to keep a deep-water species or a species like Eledone that require a temperature of less than 15 deg C but your room temperature is too hot? Well you would need to either go for a tropical species of octopus or buy a chiller. They are expensive but necessary for cold water species.
Octopuses require a high level of oxygen to be present in the water. Using an air pump with wooden air diffusers to agitate the surface layer of the water can do this. This allows waste gasses to escape and beneficial gases like oxygen to enter the water. A test kit is available to check on oxygen levels.
An octopus has no real lighting requirements. That does not mean to keep it in the dark but bright lights and sunlight are to be avoided.
The best light to use would be a normal fluorescent bulb made for home aquariums on a timer set for 8 - 10 hours of light per day. Normally I set this to ensure that the octopuses' day time if it is a diurnal species coincides with when I am home. So, mid afternoon for the octo tank can be 9pm for us if you plan it right. It just means that the octopus will be active when I am home.
Well, there are lots of things that come into play regarding keeping octopuses and other cephalopods in the home aquarium. I have tried to cover the most important, fundamental issues pertaining to their husbandry but this will get you started.
Don't be put off by unfamiliar words and phrases if this is your first time keeping marine animals! There are lots of sites available on the web where you will find explanations or why not post a message to myself and other community members on the Ceph Care category on the message board? You will get there eventually!
Colin Dunlop, Monday, 02 September 2002