[Octopus]: 1st octopus

Jun 16, 2015
Finally received my first octopus. Was advertised as a "brown pacific octopus" from saltwaterfish.com. Any help on some proper identification would be appreciated! It's about an inch or 2 when its all curled up and maybe 3-4 inch arm span stretched out from tip to tip


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Also, it was hard to get a clear picture but it had some sort of lines up and down it's legs. Turned from brown to orange it was flashing some colors at me while acclimating, probably pretty stressed from the shipping. What's good to start feeding an octopus of this size? Going to call the place i got it from and ask what they were feeding it. I have some shore shrimp, hermits, snails and a few clams for it chase around whenever it wants. The tank is 125g so it has plenty of room to stretch I hope I get to see it again soon. I'll post tank pics tomorrow
Unfortunately, the pictures are not terribly helpful but I will give you my first impressions and thoughts.

The large eye to mantle ratio, mantle to arm ratio and red(ish) coloring have me first guessing a nocturnal dwarf. The most common we see that fits those thoughts is O. mercatoris. Here is a search list of our media for this species for you to examine and compare.

Some keepers have been able to use hermits but only my vulgaris ate hermits or snails (she at ANYTHING :biggrin2:). My mercs all ate freshly killed (but had difficulty catching live after they were a few months old) shore shrimp (offered on a stick - tricky to accomplish) and live fiddler crabs (any small live crab is usually accepted).

For many, I could not get them to eat table shrimp (thawed shrimp from the seafood section of the grocery) but with the last couple I kept, I discovered that offering eye sized pieces were accepted. I think that I offered far too large a piece to the others and they did not consider it food.

You can try offering a clam on the half shell but if my guess is correct, the dwarfs would have a hard time opening a live clam. Mussels and oysters can also be offered but they tend to make a mess in the tank and I stopped feeding them.

If you have a local Asian/seafood market that has live blue crab you can also try offering the claws (we scrounge the loose ones - don't remove any still attached or the market will be unhappy with you). The claws can be frozen and thawed for later use. For an animal this small (and for a newly acclimated animal even of a larger size), I crack the claws before putting them in the tank.
Local Asian market isn't very local but their live seafood is way too big for it. I am thinking about having a spare 5.5g tank that's floating around become a holding tank for some freshwater ghost shrimp. Are those with the occasional clam on the half shell enough nutrition? It's still hasn't appeared yet but going to try to lure it out with a clam and maybe some krill on a stick (if it eats krill). Also I have been looking up the mercatoris that seems like a pretty accurate ID. Bummer it's such a small little guy in a huge tank I'll never see it haha.
Unfortunately, mercs are one of the few we see where a tank can be too big. They can be kept in something as small as a 15 gallon tank with good water care. My mercs pretty much all lived on fiddler crabs and shore shrimp (and later small pieces of table shrimp). I have grown out 2 tank hatched generations (one from a wild-caught mother, the second from tank bred siblings), first feeding frozen Cyclop-eeze (no longer available) and later switching to shore shrimp and fiddlers. You can search our journals for "mercatoris" but here are two older but most complete journals.

Varys' babies - (gholland) includes a link back to the original wild-caught mother.

Tapper's babies - (mine) includes links to the original wild-caught mother and forward links to the grandchildren.
I saw the octopus for the first time since acclimation last night at like 3am. It was eating a nerite snail so I'm glad it's doing well and eating! Since it's so small I think I'm going to just keep a stocked clean up crew and try to get it to eat a clam on the half shell. Hoping to see it again tonight! I got a red light so as not startle it and we can check each other out. It was mostly hidden in the rocks with only an eye and it's tentacles out so I couldn't get a clear picture
Clams may be too big for dwarfs/small octos but I have not tried them. As a general rule of thumb, offer food about the size of the eye. I start feeding newly acclimated animals this way, regardless of their current or eventual size. Once they are taking food regularly, feel free to experiment. If you can source some fiddler crabs (Paul Sachs is always a reliable supplier if you want/need to order on-line), they (as well as any small crab) are almost always accepted and are a quality food. I recommend disabling any sharp claws. You can remove them or break the tips (particularly on the large claw of the male fiddlers, I don't worry about the females or the smaller pincer).
Yes, a bucket will do (should have high sides) with some kind of island (rocks are fine but anything aquarium safe works). I keep mine in saltwater but they can be kept in fresh (no chlorine). You will need to change out the water about once a week (or if there is an odor).
Got some awesome footage tonight really was showing off color changes. Was going all over the tank first time I've seen it do that. Ate another nerite if you can see it dragging it around


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It has been coming out regularly from like 12-3am. I haven't seen it eat anything other than nerite snails so far there is a collection of shells growing outside his tank. Gonna try to give it a clam on the half shell tonight haven't been able to get it to eat that yet. He is also bigger than I initially thought so I'm guessing it's older. Arm length is about 3-4 inches while stretched out. I got a good look at its mantle last night and noticed it was slightly pointed which I have seen in octopus mercatoris pictures not sure if that's a universal thing that happens
The mantle shape is very flexible. Some are more muscular or slimmer but they all can alter the shape to a high degree so it is not often useful for id. We often see a "cone head" display on most of the species we keep. Sometimes with a dark or light "skunk stripe" is displayed at the same time.

I did a presentation for TONMOcon several years ago. You can see the outline here. Click on the presentation screen, then on "Identifying traits" under the picture of my breakfast (octo) room for images and best guess characteristics. The outline on the left slides to the topics. Clicking on the camera icon will display pictures. Note the Displays that Don't Identify section and the Cone Head images. Sometimes you will also see a little pigtail at the tip. I aways wonder if the excess skin is gathered there but it may serve some other, unknown function.

Unfortunately size, to an extent, is not a good indicator of age. It seems that all species vary widely even among siblings.
Of course! Here is an even better video I just got. It tolerated my phone light for about a minute before shrinking back into it's hole. Eating another snail


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