Octopus antics
Octopuses are interactive, intelligent and appealing. Jason Scott of The Water Zoo explains the difficulties inherent in keeping these specialised cephalopods.
Copyright © Practical Fishkeeping
Over the past twenty-five years or so I have kept a wide range of strange and unusual marine species; everything from sharks and rays to Frogfish and Flying gurnards. In this time I have accumulated a good deal of knowledge about how to care for the weirder aquarium inhabitants.
For many years, keeping an octopus had been a really appealing idea - I was fascinated to learn for myself whether the stories regarding their intelligence and camouflage were true. I had heard rumours that they were extremely difficult to keep but, always ready for a challenge, I decided to take the plunge.
Early problems
The first problem I came across was a complete lack of information on keeping an octopus in a home aquarium. I found lots of information about various species, but absolutely nothing about water conditions, filtration, aquarium size, behaviour and other crucial factors.
The first aquarium was 68 l./15 gal. 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 10 Kg/22 lbs of live rock.
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 diurnal octopuses, for example, colour changes.
It fed well on cockles still in their shell and it used the empty shells to form a barricade to its hole in the live rock where it lived. This did well for two months, before it got stuck behind its own barricade. It was trapped for several days before I realised and when it was released it was very distressed and died the next day.
Over the next few months I tried to keep octopuses in this aquarium on several occasions without success. They did well initially, but then stopped feeding and then deteriorated very quickly. I tested the water frequently and never found anything to be concerned about.
Unfortunately I was not sure what the parameters for octopuses should be. In hindsight there may have been inadequate oxygenation and circulation or a low s.g. I had never been so unsuccessful in keeping any species before and octopuses were rapidly loosing their appeal due to my failures. I decided to throw everything I had (including over two and a half thousand pounds) at one last attempt...
Resources at the ready
I purchased a 91 x 66 x 51cm/36" x 26" x 20" custom-built aquarium designed to house an ab Aqua Medic Marin 500 internal filter, this includes a large air-driven protein skimmer, trickle filter and a D and D Sulphur Denitrator. The Marin 500 is rated for tanks up to 590 l./130 gal., I installed it on my 181 l./40 gal. tank to ensure that inadequate filtration was not going to be an issue.
I wanted to be able to monitor water quality precisely 24 hours a day to give me the earliest possible warning if something was wrong. To do this I chose the IKS Aquastar and equipped it with pH, temperature and oxygen probes. I also added an air pressure sensor to assist in calibrating the oxygen probe and a redox probe to ensure correct functioning of the denitrator. All the monitored water quality parameters are stored every hour and are downloaded to my PC. The IKS unit also was set up to control the heater and the fifteen watt Gro-lux fluorescent light for use during the day and some tiny red LEDs for night lighting.
The aquarium is decorated with around 50 Kg/110 lbs of well washed Tufa rock, as I knew from previous experience that providing plenty of hiding places was essential. I also added some artificial corals and few pieces of marine safe plastic pipe, for the octopus to explore.
Once all the equipment was in place, any gaps around the sliding covers were filled with silicone to ensure it was escape proof. I also found a glass lock to enable me to lock the covers shut.
I filled the aquarium with reverse osmosis (RO) water and ran it for a few days, primarily to check everything worked as well as ensuring that the rock and pipe work would not leach any toxins. I was being ultra cautious this time round.
Everything worked fine so the aquarium was drained and refilled with RO water and the salt added. Once the aquarium was up to temperature I added a bag of live aragonite mixed with coral sand to the base to give a substrate about 2.5cm/1" thick. The live aragonite matured the system in just a few days.
Lucky find
Even for someone in my position (I work in the aquatic 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 meantime I added a Domino damsel to keep the filter ticking over. A few days later I visited Tropical Marine Centre and to my amazement they had a single Octopus vulgaris with arms about 13cm/5" 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.
Once I got home with my new purchase I tried to acclimatise it as is normally done with marine livestock. The octopus had different ideas - it been in the bag for about five hours and was keen to leave as it climbed out after only a few minutes. It immediately went and hid at the very back of the aquarium where it could not be seen. The next evening I put a cockle in shell in for it to eat, and switched off the light. In the morning I was disappointed to find the cockle had not been touched.
After this scenario had been repeated several times I was starting to get more than a little concerned. I knew healthy octopuses should have a voracious appetite. I wondered if the Domino damsel was unsettling it, so the next night I decided to remove it. That night I tried a cockle once more and in the morning it had vanished, so at least I knew it was now eating.
Sudden surprises
Over the next week or so the octopus started to come out more and more. The first time we saw each other, we were both startled - I jumped and the octopus ejected a cloud of ink. This did not appear to cause any problems. I gradually increased feeding to three cockles per day, but nitrite rose to 1 ppm. I counteracted this by changing 25% of the water daily, reducing the feeding and adding a Polyfilter. Surprisingly, the nitrite did not seem to bother the octopus as much as it did me!
After two weeks the water quality was near perfect (NH4 0 ppm, NO2 0 ppm, NO3 0 ppm PO4 0.01 ppm, pH 8.2, s.g. 1.025) and the octopus had already learned to associate me with feeding time.
This time it looked as if I had finally succeeded until one night, to my horror, it started to act very oddly. It was rapidly wrapping its arms around its mantle and appeared to be almost turning itself inside out. I immediately changed 25% of the water and added activated carbon and the next day it seemed fine. I later found out that octopuses sometimes clean themselves by rubbing their body (mantle) with their arms, which seems a likely explanation.
Extra equipment
After this incident I decided to add some extra equipment and invested in a UV steriliser 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.
Even with all the equipment I still change 25% of the water and test it each week. I clean the protein skimmer and pre-filter daily and a polyfilter is kept in the aquarium at all times as a precaution and replaced fortnightly. Despite all the water changes, I still find phosphate to be a problem unless I use Rowaphos. I have no problem with nitrate due to the high level of water changes and denitrator.
Thoughts for the future
By the time you read this article I will have kept my octopus for over six months and each arm is now 45cm/18". In this time the octopus has learnt many skills; it can open almost any sealed container and will even climb out of the water to take its food from me. It still hides for much of the day, but is nearly always stuck on the front glass in the evening waiting for me to come home.
I have found octopuses to be every bit as intelligent as I had read. Everyone who has ever seen my octopus do one of its party tricks have never been anything less than astounded. Without doubt they require more time and effort than anything else I have ever kept, but they are well worth the time and expense.
I have finally been successful at keeping octopuses, as in their natural lifespan is only one or two years at the most. I'm now looking to keep more challenging cephalopods, such as cuttlefish or even Nautilus, but they will need a bigger aquarium.
Octopus facts
1.Their brain is donut shaped with their stomach passing through the centre.
2.They have excellent senses, especially vision, smell and touch, but they are thought to be deaf.
3.A large proportion of the nervous system is in the eight sucker-covered arms.
4.Octopuses have three hearts and blue blood.
5. Males die shortly after breeding; the females tend the eggs until they hatch, after which they also die.
6. Even if they never breed their natural life span is only one or maybe two years depending on the species.
7. Octopuses have no bone structure, as they are invertebrates, despite this they are incredibly strong.
8. They are intelligent and require mental stimulation in captivity to prevent them from becoming bored.
9. There are less than a handful of people in the UK who keep them.
10. They are best kept on their own, most tank mates make a tasty meal.
11. Colour, texture and even body shape can be altered in an instant.
12. They can squeeze through tiny gaps.
13. Ink can be ejected to confuse would-be predators.
14. When swimming, octopuses use jet propulsion, a bit like a jet-ski.
Octopus aquarium equipment
This is a breakdown of the equipment that I used in order to keep an octopus successfully.
> 40 gallons (190 litres) 36X26X20 Seabray aquarium and cabinet, £325.00
> Aquamedic Marin 500 internal filter with skimmer, trickle and nitrate filter £409.95
> Rena 300 airpump £29.95
> Airline £1.60
> 200w heater £22.49
> Additional thermometer £1.79
> Polyfilter £11.95
> Rowaphos (phosphate remover) £8.49
> Minjet 404 to operate UV and chiller £18.75
> 8w Vecton UV £69.95
> Teco Micro chiller/heater £299.95
> 50mg Ozonizer £114.95
> 15w Arcadia starter unit £14.95
> 15w Arcadia original lamp £6.49
> Miracle beam hi-lite starter set(night lighting) £27.50
> IKS computer controller £159.90
> pH probe £129.95
> Temperature probe £83.95
> Redox probe £144.95
> Oxygen probe £219.95
> Air pressure sensor £76.75
> IKS plug bar £94.95
> Data lead to connect to PC £24.50
> Live aragonite sand £31.95
> Salt mix (Kent) £20.49
> SeaTest hydrometer £15.95
> Ammonia Alert £8.95
> Merck PO4 borrowed
> Nitrite and Nitrate test kits froshop when needed.£14.78
> 50kg Tufa rock £60.00
> Artificial corals £25.00
> Background £14.70
> Electrics, plugs, sockets. £25.00
TOTAL £2,515.48
I also added air conditioning to the room! £400.00 This helped me and the Octopus keep cool. While not absolutely every item of equipment listed here is needed, I believe that anyone contemplating keeping such an intelligent animal should provide it with the best environment possible.
Word of warning
The difficulty of keeping octopuses 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. They also have a short natural lifespan which means that the relationship that develops with this interactive, intelligent creature has inevitably upsetting consequences.
Those who wish to learn more about octopuses should visit www.tonmo.com
I did not find this website until I had learned how to keep octopuses the hard way. Colin Dunlop is their expert on octopuses and cuttlefish and has kept several species successfully.
Jason Scott 2115 (words, 9097 hits)Published online: 03.14.03
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