“It’s not rocket science, but....”
The following discussion is written somewhat to those that might want to observer octopuses or cuttlefishes in a somewhat natural environment. If your need is to simply house cephalopods for research purposes, the basic precepts outlined still apply even in the laboratory environment.
If you’ve never kept a saltwater aquarium before, Cephalopods (cephs)
can be a challenging animal group to start with. The nuances of keeping marine fish and
invertebrates require a bit of a learning curve (This may be a slight
understatement). In general, octopuses and cuttlefish require greater attention
to water quality and husbandry skills than most marine tropical fish and
invertebrates. This is to take nothing away from those who keep live corals or
spawn tropical fish etc, but cephalopods will sometimes die almost immediately
in a system that keeps live corals in beautiful shape. They are just different
beasts. Let’s say they are less forgiving of your shortcomings.
Now, it is possible for a complete novice to pull this off but the odds
favor those with some experience in the craft. If you are a novice, read
everything you can get your hands on about the salt water aquarium. You need to
understand the biological, chemical and physical processes that are determining
the water quality in your aquarium (I’m not saying here you need to be able to
do the bicarbonate buffering equations for a given pH and temperature combo!!).
This basic understanding of the processes will become especially helpful if we
find our selves in a problem solving situation later on trying to figure out why
you might be having problems. We’ve got to be able to speak the same language
to sort things out. OK, so we’ve established that
knowledge is GOOD, ignorance is BAD. Excellent.
The
“Skinny” on Cephs
Next, why are cephs more tricky to keep healthy? It’s my opinion the number one thing that makes cephs more sensitive to their aquatic environment is that they all have a “microvillus” epidermis. That is the kind of lining our intestines have to maximize adsorption of nutrients as food passes through. This means that the skin of cephs isn’t smooth but rather covered with millions of tiny finger-like projections giving the skin a huge surface area in contact with their watery world. If you held an octo in one hand and a fish of similar weight in the other, the fish might have a total skin surface area of say one square foot. The octopus on the other hand has a surface area of something like your living room. A cephalopod has huge exposure to the water it lives in while a fish has scales that actually cover its skin, a crustacean or clam has a shell to minimize exposure, a coral polyp can retract into its carbonate condo, and so on. But a ceph has nowhere to hide from nasty little ions floating around in the water. This is why I think that many other marine reef inhabitants can survive just fine in a given situation because they have limited contact with any nasty toxic ions floating around. However, when you then add an octo, they are totally exposed and can die within in hours or a day maybe. So we want to be very careful to control what is in our seawater at all points. Also, I’m not saying that you can’t have cephs and other marine creatures in the same aquarium or on the same seawater loop, you just have to keep your finger on the pulse of water quality and make decisions based on your most sensitive inhabitants.
“It’s
the Water!”
Next thing to remember is that cephs really like full strength seawater,
not the watered down stuff lots of folk keep their fishes in. Of the hundreds of
species of cephs, perhaps less than ten ever frequent reduced salinity environments.
Normal seawater is about 35-36 ppt (specific gravity of something like 1.024).
That should be your target. Keep in mind that many tropical marine fish do just
fine in 10-15ppt water, amazing. Don’t try this with your octopus (octo) or cuttlefish
(cuttle) or
they’ll do something akin to what happens when you put water on the Wicked
Witch of the East. Well, not that dramatic but remember: low salinity for cephs
is BAD. Excellent.
Next, some guidelines for water quality to keep in mind. The one thing
you should monitor weekly at the least is pH or acidity of the water. You can
get some pretty simple test kits to check this at any aquarium store or
supplier. Aim to keep pH between 7.8 and 8.2. Octos will actually survive pH
down to 7.7 but you’re looking at getting to know a new octo real soon if you
let it stay here for long say over a week or so. It is also indicative of system
problems so you need to address it immediately anyway.
Next is the Nitrogen Big Three, ammonia, nitrite and nitrate. If you can
afford it I recommend measuring Ammonia once a week, to me it’s sort of like
checking blood pressure, you’ll see problems here first if the patient is
getting weak. Ammonia(NH3-N) should stay below 0.05ppm ammonia-nitrogen. If it
gets to 0.1-0.5 ppm and stays there this is BAD. A good biological filter should
be able to maintain levels below 0.1ppm without a problem. Next thing is
Nitrite(NO2-N), which is the breakdown product of Ammonia. It goes hand in hand
with Ammonia swings but we’ve determined over the years that nitrite is more
toxic to cephs than ammonia. That’s why it’s so important to track ammonia
because where ammonia goes, nitrite follows and where a high ammonia level
doesn’t croak your critter, the same level of nitrite a few days later will.
Usually, it is the smoking gun that tells you why your animal died or nearly
did. Nitrite is BAD. Last comes Nitrate(NO3) which is sort of like flatulence
after a good Mexican meal, harmless to annoying at low concentrations but
potentially lethal had very high concentrations unless you roll down the window
(i.e. do a water change). Cephs can handle nitrate levels up to 100ppm but they
are not happy campers above 50ppm. Cuttles in particular start to ink constantly
when nitrate-nitrogen goes above 75ppm. You know you’re there when you haven’t been
able to actually see your cuttles (or anything else for that matter) for a
couple of days. Do a water change. I hesitate to say this but I have kept
octopuses at up to 400ppm (by accident) and they were doing fine but I don’t recommend you do this at home.
Making
your Seawater
We recommend two brands of artificial sea salts for cephalopods, those
being Instant Ocean and HW MarineMix. This is no commercial endorsement, we
don’t sell the stuff or get a kickback from them (I’d point out we are open
to the idea, but they never seem to call.) Are they the only ones that will work? Certainly not, but we KNOW these
two do. There have been several occasions over the years where I’ve
troubleshooted every conceivable source of problems and finally got down to
trying one of these two sea salts and presto-keeno, no more problems.
The next most important decision you’ll make is what to mix these sea
salts up in. Please don’t use tapwater. Tapwater is BAD. Distilled, deionized
or reverse-osmosis water is GOOD. If you have to go to the grocery store and buy
the 25 cents/gallon water from the water machine, it will be $$ well spent.
Don’t think that the myriad chemical mixes that supposedly clean up tapwater
will make your tapwater safe for cephs. Go back and read the section above about
the microvillus epidermis of cephs and understand that using chemicals to remove
chemicals will still leave chemicals. If you go ahead and use these products,
don’t waste your dime calling me if your critter croaks overnight after
getting him. Just don’t use tapwater, period, end of statement.
It’s always a good idea to age your seawater several days to a week
before putting cephs into it. Also, we recommend having a reserve batch of
seawater mixed up at all times equivalent to about 25% of your total aquarium
system volume for emergency water changes. This is a bit of a luxury I suppose,
but man is it nice to have when you do an ammonia test and the #’s aren’t
good and your octopus doesn’t seem to know which way is up. Of course you
should cover this reservoir and keep it gently aerated. A dedicated 30gal
polypropylene garbage can works great for this purpose.
Recommended
Filtration Strategy
Well, I suspect that by now you have gotten the idea that cephs need good
water quality. That's GOOD. Now how do we actually accomplish that? Well, you’ve
got about a hundred options but here is what’s got to happen. First and
foremost, you need a biological filtration system that just munches to the max
on ammonia. I’m talking kick butt, total annihilation. You can’t have too much
capability. Interesting factoid, compared to an
equal biomass of live fishes,
the same live weight of cephalopods will produce approximately 3 times as much ammonia
as those bug-eyed fishes will. THREE TIMES AS MUCH. You need
a good biological filter, enough said. I’m old school (probably because I’m
old) and will stack a good ol’ crushed oystershell subgravel filterbed up
against any new fangled European gizmo filter for removing ammonia. Will living reef systems work? Probably. Will
live rock work? Probably. Will bioballs work? Probably not! Get a real
bio-filter, not something with bioballs (old school attitude showing again,
sorry, but honestly I don’t think they work worth a darn compared to anything
else). I like to have my total water volume pass through the bio-filter once
every couple of hours as a minimum. That will assure you that ammonia gets yanked out asap.
Particulate filtration is important. Octos and cuttles are sort of messy
critters, they’re covered with slime for starters and poop right out in the
open. Other than that they’re quite charming. They also shed things called
sucker disks from each of their suckers daily and these things are always floating around. Then
there is just all that miscellaneous organic gradu that all aquariums produce
mysteriously. You can use polyester fiber batting, pleated filter cartridges,
whatever, but it should be rather fine filtration, not window screen sized mesh.
Good quality Activated Carbon in your system is simply essential. I’m
not really sold on carbon in a mesh bag just sitting in a sump. Try to create a
system where your water must flow through the carbon. Carbon does so much good
for you. It keeps your water clear and colorless, removes ink and dissolved
compounds from the food your feeding, etc., etc. Don’t skimp here. Forget
cheap coconut carbon. Get good stuff, it’s $$ well spent again.
Protein skimming and U/V sterilization are nice, but if you’ve only got
one animal or two, they are icing on the cake but probably not essential. Here,
where we’ve got dozens to hundreds of animals they are vital. At low animals
loads like you probably have you can save some $$ here if you want to. If
you’ve already got them, great, use them.
The last thing is that I like a lot of aeration. A couple of airstones or
airlifts will do wonders for the water, keep surface scum from forming on the
water surface and keep your critters alive if the pump short circuits the minute
you walk out the door.
So I’ve tried to cover the basics of setting up a good healthy
environment though I’m sure I’ve not
mentioned everything.
General
thoughts on keeping octopuses.
Probably
the thing that octopuses are most famous for among aquarists is their propensity
to crawl out of tanks. Fortunately, not all species are kamakazi’s about this.
Octopus bimaculoides and O. cyanea
almost won’t do it, O.vulgaris and O. briareus can’t wait to! But any octo
might, so take some precautions to at least make it a bit challenging for the
‘ol boy. You can use a hinged glass or plexiglass top with openings cut in
them for plumbing entry/exit. A couple of dive weights or bricks will dissuade a
half-hearted escape attempt typical of those species not particularly inclined
to try. But keep in mind that if you have a larger octo, say as big as a
grapefruit when all balled up, well, that’s sort of like having Arnold
Swartzeneggers bicep in your tank. If the octo exerts maximum push at one point,
it can lift a lot of weight. So if you’re clever, you need to design an
immovable lid design, in other words something that clamps, locks or buckles
down. Mere weight will not always do the job.
Octos don’t per se need a lot of space. so tank size is really up to
you. It’s more fun to be able to watch your octo cruising around and checking
things out in a 55 or 75 gal tank than living in a beer can in a 10gal tank
where he can touch all the walls without leaving home. Bigger tanks obviously
offer the buffer of more water should pumps etc fail for several hours, thus
keeping water quality better until you figure it out. Octos do need something to
live in. Virtually anything is suitable that they can get inside of. I’ve
found them in paint cans, bicycle frames, swim fins, shoes, you name it. Ceramic
things are a good choice, flower pots for instance. You can get creative and
build a rock grotto or just give the octo a bunch of shells, rocks and coral
pieces and they’ll build their own den site.
Octos have a sort of nasty habit of eating just about everything else
alive that you put in a tank with them that is their own size or smaller.
Fishes, other molluscs and just about any crustaceans are in some danger. Soft
and hard corals would not be at risk, sea stars should be ok. Most folks keep octos by
themselves but there are exceptions. Talk with your friends and see what their
experience has been.
Most octos will adapt to frozen fish or shrimp as a primary diet. It is a
ton of fun to occasionally invest in a live crab and watch your octo go into
“Terminator” mode. That crab will never know what hit it. Octo’s don’t
really like fish that much but they will take adult guppies or goldfish as a
pleasant change from a steady diet of frozen fish or shrimp. You should plan on
feeding your octo at least every other day. If you were to have two or more
octos together, or an octo with some other reef creatures, then you better feed
it every day to be safe.
Octopuses have comparatively short lifespans. Most tropical species live
a year or less. Cooler water species may stretch that out to 18-20 months after
hatching. So it’s no wonder that so many people buy an octo at the pet shop
and it dies or lays eggs after a month or two. They’ve already gone through
their normal lifecycle in nature by the time they are collected. That’s why
farm-raised is the way to go when possible because “we know how old they
are!”. The local aquarium shop never does. Heck, they never know what species
they have. So, be warned, you WILL fall in love with octopuses, they are so
cool, but they WILL die in a year-or-so or less even when you do everything
right. That’s the price of having the neatest invertebrate in the ocean in
your living room. You just can’t argue with Mother Nature.
So
You’re Thinking About Trying Cuttlefish? Some things to think about.
Cuttles really need more tank space than octopuses, and they need
horizontal space, not vertical space. Choose a display tank that maximizes the
horizontal dimensions. If you had a tank 24 inches deep, you’d virtually never
see a healthy cuttle in the top 6-12 inches. They stay near the bottom. You can
decorate your tank no problem with coral rock or what ever. They are pretty
smart and don’t run into that stuff. You can also build an overhang or grotto
for cuttles too and they’ll hang out there often. Cuttles tend to be more inky
than octos when they are frightened unexpectedly or even expectedly for that
matter. It’s worse when they are small. As they get older they calm down significantly. After a few months you should be able to have your cuttle taking
food right out of your fingers (they never take your finger!).
As for food. pretty much what I said about octos applies to cuttles. In
fact, everything! Same diet. They never met a crab they didn’t want to have
over for dinner, literally. They like fish a bit more than octos do but shrimps
and crabs are their favorites too. Again, they should be fed daily if you have
two or more together, otherwise every other day should be fine. And if you feed
them a live crab, don’t blink or you’ll miss a lightning quick feeding
attack.
Well,
this should get you started. These are general comments. Check out the species
characteristics of the species you intend to get on our “Species
Information” pages. A few more specifics there on each species. We always want
to know how you’ve done and what your experiences have been so let us know.
I’ve never met anyone that had an octopus or cuttlefish that wasn’t hooked on ‘em
afterwards. After all these years,
we’re still hooked too!
Good
Luck and have a ton of Fun.