Octupus, although one of the most interesting and intellegent creatures that one could keep in home SW aquaria, are notoriously difficult to keep. They must be kept singly in their own tank, are known to attempt to escape from their tank, and must be kept under prestine water conditions. Being that they are carnivores, they will need meticulous regular water changes, carbon filtering, and protein skimmers. They often do not ship well and can be difficult to acclimate to a tank setting. They often require live food consisting of crabs, shrimps, or fish. They make a mess of their tank by discarding the undigestable body parts of their food. They will require a hiding place somewhere within the tank to call home, and will spend the majority of their time there. When frightened, they will release their "ink" to confuse their perceived enemy. The usual species to be found in LPS require a minimal tank size of 30 gallon. Most species have a life expectancy of only 1-2 years, and die after spawning.
With that being said, they are absolutely facinating creatures. They can crawl through any hole that they can squeeze their head through. They can change their body color and texture to mimic their immediate environment in a split second. They are quite intelligent, and quickly learn to recognize who feeds them. I kept a small octopus for a couple of months in a 29 gallon tank many, many years ago. Unfortunately, old "scrotum head" gradually declined to where I found his white lifeless body one day. I presume the water quality was not up to par, as I only ran an undergravel and outer power filter with carbon along with water changes. Skimmers were far to expensive back in those days, and wet-dry filters were just beginning to be used. Even with today's technology, keeping an octupus healthy is very challenging for even the most experienced acquarist.
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