tonmo said:
What I'll do is link to this thread from that article, so people can discuss its contents here .
Greetings,
Since the link between Jason Scott's article Keeping an Octopus and this thread was provided in answer to a suggestion of mine (Thanks Tony!) it seems only fair that I contribute my two cents worth of critique.
First, what follows is not meant to be a criticism of Mr. Scott personally. I think his article reflects an honest effort to provide proper care for the animals he tried to keep. Unfortunately, the article seems to present a significant number of errors and misunderstandings that could, I believe, cause new hobbyists to either avoid or adopt octopus keeping for the wrong reasons.
I've numbered the paragraphs of the original article and quoted them in red. My own comments follow each cited paragraph in black:
#4
The first aquarium was fifteen gallons and equipped with a Bak-Pak skimmer with built in biological filter. An eight-watt fluorescent tube provided lighting, this was the smallest available, but still a little too bright. For decoration I used ten kilograms of live rock.
A fifteen gallon tank is almost certainly too small, even for a so-called "pygmy" species such as O. bocki. Conventional wisdom suggests that the minimum size tank for this size animal be 50 to 100% larger than the one described in the article. TONMO's own Colin Dunlop recommends a minimum size of fifty gallons and makes no exception for small breeds. [FWIW: I personally suspect that the very smallest species such as O. wolfi could be kept in a somewhat smaller tank.] It's important to remember that tank volume has two functions; to provide living space for the animal and to provide a sort of buffer to absorb 'chemistry spikes' from the octo's very active metabolism.
5
After the aquarium was matured I obtained a small Red Octopus, I later found out this was an extremely nocturnal species (Octopus bocki). Identifying any Octopus correctly is difficult, even for experts. This species only comes out in complete darkness and does not exhibit many of the character traits associated with other more day active Octopus, for example colour changes. It fed well on cockles still in their shell; it used the empty shells to form a barricade to its hole in the live rock where it lived. Any way this did well for two months, before it got stuck behind it's own barricade. It was trapped for several days before I realised, when it was released it was very distressed and died the next day.
I have a couple of problems with this paragraph. First, why is it that people who will spend whatever time and money is necessary to obtain the exact species of fish, coral, or even worm seem perfectly satisfied to buy whatever octopus happens to show up at the LFS? The author had the good fortune to receive O. bocki, a species that doesn't get very big but consider what might have happened if he's gotten an O. vulgaris instead. If the animal didn't die prematurely from stress or ammonia poisoning the tank would have eventually gotten so full of octopus that there would hardly have been room for water. Second, "stuck behind it's own barricade"? The author is describing textbook octopus maternal denning behavior and his own conclusion that the animal had somehow trapped itself is just not supported by the facts presented or by simple logic.
6 through 11
Even for someone in my position (I work in the aquatics trade) obtaining an Octopus requires a bit of luck, they do not always travel well and it is hit and miss what species you may get. In the mean time I added a Domino Damsel to keep the filter ticking over. A few days later I visited Tropical Marine Centre, to my amazement they had single Octopus vulgaris with arms about five inches long. This was my lucky day, it was only the second time in many visits I had seen anything other than the commonly imported nocturnal species. I was aware that the aquarium had only just matured, but this was just too good an opportunity to miss, I had to have it.
At this point the author has spent hundreds or even thousands of dollars on equipment to monitor his water quality but we have seen no indication that he's done any research into what his water parameters should be. He has an 80 gallon tank that contains a fish known to be extremely territorial and aggressive. Now he buys, almost on impulse, an O. vulgaris to keep. The problems here are all about size. When he brought it home the octopus was apparently too small to deal with the aggressive damsel. On the other hand, this species would have outgrown an 80 gallon tank long before it reached its maximum size. Fully grown, O. vulgaris can be up to 5 pounds in size and, according to Colin Dunlop's excellent article, an octopus can produce waste equal to three times its weight in fish. Consider an 80 gallon aquarium housing 15 pounds of fish - not a tenable situation.
14
After two weeks the water quality was near perfect (NH4 0, NO2 0, NO3 0 PO4 0.01, pH 8.2, S.G. 1.025 and the Octopus was had already learned to associate me with feeding time.
Later in the article he shows a table that reflects increases in nitrate and phosphate (albeit not harmfully higher) a pH of 8.0 and oxygen at 90% of saturation. the pH and oxygen levels are probably related and are somewhat problematic for an octopus. Octos have a high metabolism but their use of oxygen is inefficient because of their copper based blood (as opposed to our iron based blood). What that means is that,even under the best of conditions, an octo tends to tire easily. With a reduced amount of oxygen available the animal probably feels a bit like a human with a mild case of asthma.
15
This time it looked like I had finally succeeded, until… One night about 10:00pm it started act very odd like it was turning itself inside out! I was horrified, I immediately changed twenty-five percent of the water and added carbon. The next day it seemed OK. I never did find out what caused it to act so strange, but Octopus sometimes clean themselves by rubbing their body (mantle) with their arms, I was not aware of this at the time.
Here again, the author is worrying over a perfectly normal and regular octopus behavior. The writhing action is performed mainly to help shed the old epidermal layer of its suckers. This shedding is necessary for the octopus to properly sense his environment. Octo suckers are truly multi-tasking pieces of equipment. They're not only used to grasp things but are also the animals major touch sensor and an important part of its sense of taste/smell.
16
After this incident I decided to add some extra equipment and invested in a U/V sterilizer and chiller. The chiller is excellent, on all but the hottest days it keeps the temperature at exactly 25°C, With some of the exceptionally hot days we had this Summer I'm sure the Octopus would have really suffered without it. Since adding this equipment I have never seen the Octopus act out of character or clean itself.
Apparently the UV sterilizer was added because of the (perfectly normal) cleaning/shedding behavior. If, as was claimed, the octo quit this periodic behavior I would take that as an indication that UV was contra-indicated. More likely though is that the octopus simply didn't happen to do it in the author's presence any more. The behavior doesn't generally last very long and the way you usually know that it has been done is by the blizzard of sheds floating around the tank for several minutes. [They look sort of like milky contact lenses.]
A chiller is a really useful thing to have but I question whether 25C is the proper temperature for this particular animal. O. vulgaris is among the most widespread of all octo species. In fact, there is a discussion among taxonomists about whether there may actually be several sub-species each endemic to a different environment. There was no mention of where this octopus was collected but, since the author is in Great Britain and O. vulgaris is found all along the southern coast of G.B. and Ireland where the water is quite chilly the possibility exists that he bought a British octo. A quick Google search indicates that the mean water temperature in southern England is 12C. To a sublittoral marine animal the difference between 12C and 25C is HUGE!
21
The difficulty of keeping Octopus and other Cephalopods is not to be underestimated; they certainly are not for the inexperienced. They require a good deal more expertise, equipment and dedication than many are prepared to provide.
Absolutely true! I submit, however, that the most important thing that a prospective octopus keeper can do is to learn about the specific animal he intends to keep. There is no such thing as a generic octopus. Each species has different needs with respect to space, substrate, food, temperature, escape proofing, and enrichment. Different species have markedly different lifespans (although all are pretty short) and it's all too common for certain octopodes to be sold with no consideration for how much of their lifespan remains.
22
Those who wish to learn more about Octopus should visit TONMO.com, I did not find this site until I had learned how to keep Octopus the hard way. Colin Dunlop is their expert on Octopus & Cuttlefish and has kept them several species successfully.
Best advice in the whole article!
Critiquely yours,
Alex