Mercatoris Pair Journal

Nov 9, 2008
I am starting this journal to document the lives of my two O. Mercatoris. They are coming in the next few days.

I ordered them from Dan over at
This will be my first attempt at having octopuses and am very excited.

Here's a webcam of my tank:

It's a 14 gallon Biocube equipped with a protein skimmer. The temperature in the tank is usually at a 78-80 during the day and possibly a little cooler when the lights are off at night.

I currently have 4 hermit crabs and a few snails in the tanks to start it off but will be getting some ghost shrimp and fiddlers this week. There are also two damsels in there right now but I will take them out before the octos come in.

This tank is in my office. I work long long hours and I felt that it would be a better place to keep these pets. I am in the office at an average of 9-10 hours a day and even longer during crunch time. I can attend to their needs better in the office than if they were at home.

I'll update this journal as soon as the package comes in.

[I am naming one of them Mr. Boots McKraken, and the other one might be named Huggy]
You may want to keep the lights off and top open while you are there during the day, that temp is overly warm for them so even adding a daytime clip on fan would not be a bad thing. I hope you go in late and work late and can work by monitor light or you won't see to much of them with the ambient at normal office lighting. When I viewed your webcam, the lighting looked good at night so I hope you will be able to achieve something close for part of your time with them.

Even shy mercs will often "stick" feed and can be rousted awake to eat in the early evening if the lighting is dim. I have used a long large plastic pipette but an air line tube will work (it is just harder to control and you might attach a stick to make part of it ridgid). Shore shrimp work well this way and can be partially pushed up the tube, leaving the tail out to be offered and grabbed. If you are game for hand feeding (the mercs really can't hurt you if they wanted to) you can view Wiley's only video.
Thanks for the advice D! I'll find a way to lower the temperature. What is a good target temperature to maintain?

I will have a supply of hermits and ghost shrimp free roaming the tank and plan to throw in a couple of fiddlers on a weekly basis.
How often should I "stick/hand" feed them given that I will have free roaming food in the tank?


I would recommend a max of 75 degrees and 73 is not too cold. Octos, crabs and shrimp all seem to do better at the cooler end of the Caribbean temperatures.

It would be best to try and watch how they eat. Different people have had different feeding routines that work (just like reef tanks). I feed all my octos daily (well, Neal has that task now but you get the idea). The mercs (as well as all other reported octos) will eat fiddlers and Paul Sachs sells 20 small ones for $21 shipped. Mine take shore shrimp the best and I have never seen them eating snails or hermits (others, however, have and GHolland's mercs ate/eat about anything he offers, including some frozen. None of mine would touch anything frozen except fiddlers - freeze immediately on death - NO smell, thaw in saltwater).
glad you got them. mine ate 2 blue hermits last night. and i ordered the 25 pack of shore shrimp from pauls site. see how it takes to those. and glad i read this thread. i had my temp at ~79. i turned it down to 75.
I had to move my rocks out to get the Damsel out of the tank. Now it's all stirred up and displaced. I'll wait for it to clear before I throw them in.

I floated the bags in the tank for over an hour to get them to sync temperature...
after that, I trickled drops of tank water into the bags for an hour. I then fished them out by hand and dropped them in the tank as slow as I can. The bigger dude sort of jumped in to the tank.

One crawled on the glass for a bit and may have disappeared into the sump. The other guy is behind a rock in the front of the tank.

I am assuming they will be hiding for a while.
mine hid in the same spot all afternoon yesterday. even when we went to dinner and came back he was still there. he didnt move until after we had gone to bed and it was good and dark. this morning it took me forever to find him. and then i only saw some sand shooting out of where he was and a tentacle or two. and the 2 empty hermit shells. :lol:
Stick Feeding the Mercs

I was reviewing my pictures for something else and came across these that I don't believe I have ever posted. They might help understand what I was trying to explain about stick feeding your mercs. This is my special little guy (Sisturus) who was quite human interactive (not many are) but the others would eat this way as well (just not tollerate being photographed with a flash).


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