choosing an octopus

Choosing an Octopus

The octopus is a graceful and intelligent saltwater creature. A unique aquarium animal, the octopus is not for the novice. Providing a dimly lit, safe home is crucial, especially if you want to avoid a tank full of toxic ink. This tropical sea creature must have extremely clean and properly maintained water to thrive.

Behavior and Life Span

There are several species of octopus most often found in aquariums. Most of them can change their body color at will through the use of pigment sacs. Most octopi have special red, orange, black, brown and yellow pigment sacs. They use this interesting talent to scare away potential predators, attract a mate and reveal their mood to the world. For most species, white usually indicates that the octopus is frightened. Agitated octopi may appear red.

Once sexual maturity is reached, the males tend to be a little more active than females. Some of the suction cups on their legs may appear larger and whiter. Octopi are egg layers and the male does not participate in raising the young.

Octopi are timid creatures and must feel safe and secure. This includes providing plenty of hiding places and not making any quick movements around the tank. When they are frightened or agitated, they may release large amounts of ink that contaminate the tank. If left in the tank for a sufficient amount of time, this ink will suffocate the octopus. If ink is released, an immediate 50 percent water change is necessary to dilute the ink and reduce it to safe levels.

Unfortunately, the life span of the octopus is brief. Some only live for 6 months and others, especially the larger species, can live up to 2 years. Females often die shortly after laying eggs and brooding the young. Octopi can be expensive. Since their life span is so short, buying a juvenile is recommended.


The octopus belongs to the mollusk family. It is closely related to squid, clams and snails but is unlike most mollusks in that it has no hard outer shell. As most people know, the octopus has eight legs radiating from a central body and head. Of those kept in captivity, most do not exceed 15 inches in diameter. Most weigh less than a pound. If left in the wild, some species may grow to over 30 feet.

The various species of octopi come in a variety of colors. Some may be a dull grayish color and others may have a beautiful striped pattern.


The octopus requires a pristine and safe environment. Water quality is crucial. Make sure the salinity is around 1.022 to 1.023. For most species, the water should be 76 to 78 degrees Fahrenheit (lower for cold water species). The pH must be maintained around 8.2 and there must be plenty of oxygen. The octopus is an escape artist and can escape through holes, filter tubes, etc. Any hole about the size of a quarter is big enough for an octopus to use as his getaway. Make sure all potential openings are covered with sheer stocking material and the aquarium hood is securely attached.

To keep an octopus healthy, the largest tank that budget and space allows is required. For one octopus, at least a 55 gallon tank is necessary. To prevent ink release, acclimate the creature to the water before adding him to the tank. Make sure the room is dimly lit and quiet. The aquarium lights should be off. Equalize the bag containing the octopus with the tank for temperature and salinity. Once equalized, slowly tip the bag and let the octopus swim out when he is ready.

Since the octopus is a shy creature, lots of hiding places are necessary. Coral, limestone, large shells and rocks should be provided for the octopus to build caves and crevices in which to hide. The substrate should be crushed coral or sand.

Octopi prefer living in the shadows. The aquarium can be dimly lit with a low watt fluorescent bulb during the day and darkness at night. Do not allow direct sunlight to hit the tank.

The octopus needs lots of oxygen to survive. To breathe, he constantly expands and contracts his mantle to force streams of oxygen rich water over his gills. With his three hearts, the octopus can extract plenty of oxygen from the water but has trouble transferring that oxygen to the body tissues. For this reason, the octopus requires lots of aeration. The water must be circulated with airstones or a strong pump. Octopi are very sensitive to low oxygen levels and dirty water. Filtration is crucial since octopi produce lots of urine. Mechanical, biological and chemical filtration should all be used. Every week, a 25 percent water change is required. When selecting equipment for your octopi tank, buy the best equipment money can buy.

The octopus is not a sociable creature. He should be kept in an aquarium alone. If kept with fish, you will soon find the fish have ended up as dinner. Octopi do not do well housed together since they are territorial and will fight. Octopi can be successfully kept with starfish, urchins, sponges and coral.


The octopus is a carnivore that eats crustaceans, small crabs, live shrimp, mollusks and fish. They must be fed once a day at the same time each day. Most octopi are quite messy eaters and any leftover food should be quickly removed. You may also want to consider getting a good protein skimmer.

As a predator, the octopus has a good sense of smell and a wide field of vision. Their skin is very sensitive and covered with suckers containing nerves. Eight arms radiate from a central mouth. The octopus has a tongue-like organ and rows of teeth that allow the creature to shred and ingest food. After an octopus catches a prey item, he will inject toxic saliva and a digestive enzyme into the prey to slowly begin digestion. The octopus then shreds and ingests the prey.

Most octopi prefer live food but some may eventually accept frozen food, especially if offered at the end of a feeding tong.

The octopus has been known to inflict a painful bite. Their toxic saliva is usually not toxic to humans, except for the saliva of the blue-ringed octopus (Hapalochlaena spp.). For this reason, the blue-ringed should not be kept in an aquarium.


Octopi may become ill, especially if the aquarium system is not set up correctly or the water is not clean. An ill octopus will often appear white or lighter in color than normal, will hide a lot and will not eat. This is often a serious situation that requires immediate attention. Remove anything that is stressful to the octopus and clean the aquarium if necessary.

Species Commonly Kept