Keeping an Octopus in Your Aquarium
Keeping an octopus in your saltwater aquarium isn't as common as keeping other invertebrates. One reason for this is that many octopus species grow somewhat large. Another reason is that octopuses eat a variety of fish and invertebrates that saltwater aquarists normally like to keep in their aquariums.
However, it is possible to successfully keep an octopus in an aquarium, but it will need to be a species only aquarium that houses only one octopus.
Their aquarium conditions and water quality should be approximately the same as a reef tank, although not as brightly lit, as most octopus species are noctural creatures.
The octopus species most commonly kept in the home aquarium are Octopus cyanea or O. vulgaris, however, there are other species sometimes available at your local pet store.
The octopus body is soft. There is no internal or external skeleton. Because of this, they are able to squeeze through very small openings. If you plan on keeping an octopus in your aquarium you must have a tight fitting lid. Not only are octopuses able to get through very small openings, but they are smart as well. In fact, the octopus is considered the smartest invertebrate. Because of this, if they decide they really want out of the tank they may find a way out if it is at all possible.
Keep in mind that although octopuses are invertebrates they are still incredibly strong. They can sometimes use their legs to lift the cover off of their tank.
In addition, octopuses are able to survive for short periods of time out of the water. Some aquarists report that their octopus leaves its own tank, goes across the room and enters a different tank, eats some of the fish or crustaceans, then travels back to its own tank.
However, there are also reports of octopuses drying up on the floor and dying because they didn't make it back to their aquarium in time.
To prevent this, it is very important that you have a tight fitting lid on the aquarium housing your octopus.
The octopus has eight legs (or arms) with suckers on them. They can use these suckers to attach themselves to objects in the tank. They have a large central head with well developed eyes. Their mouth is hard like a beak and allows them to tear their food.
See the excellent video from You Tube below to see a very tiny octopus using its arms to climb over a woman's hand.
If they become upset or frightened they may release ink. The purpose of this is to help camouflage themselves from potential predators. However, this ink may be toxic in the small confines of the aquarium.
The octopus also has the ability to change its color. They sometimes do this to camouflage themselves and sometimes different emotional states cause a color change.
Octopuses can become very tame. They are smart enough to know who feeds them. Plus, because they are so smart they need to be entertained. Research studies have shown that octopuses are even capable of observational learning. There was one study I heard about years ago that demonstrated this observational learning. First they had an octopus watch another octopus playing with a ball in a particular manner. Then when they gave this octopus the ball it played with it in the exact same way as the first octopus did, which indicated that the octopus learned how to play with the ball from watching the first octopus.
Octopuses can also learn how to open jars and bottles and to do many other tricks. Because they are so smart you must provide your octopus with some form of entertainment or it will get bored since it will be in an aquarium all by itself with nothing to do. You should provide your octopus with some toys to prevent it from getting bored.
Feeding Your Octopus
The suckers on an octopus's legs not only serve to allow them to climb, but also as taste buds. They are able to taste food with them.
They are carnivores and must have a diet of meaty foods. Live foods are best - not only because they are more nutritious, but chasing the prey around the tank gives your octopus something to do.
However, you don't always have to feed your octopus live foods. You can give it frozen (thawed first of course) squid, shrimp, and other meaty seafood.
In their natural habitat octopuses eat invertebrates and small fish. Using their beak they are able to crack invertebrate shells to get to the meat inside.
Octopuses can become very tame and can be hand fed. See the short You Tube video below for a demonstration.
Octopuses belong to the class Cephalopoda, which includes the squid and cuttlefish.
Unfortunately, octopuses don't live very long - about 1-2 years at most, and sometimes less.
For more information on keeping an octopus in your aquarium please see Housing an Octopus.