Live rock set up


Blue Ring
Feb 26, 2012
I am new to keeping an octopus and I have a 55 gallon, hexagon shaped tank at the back right corner of my room. I have three damsel fish (I'll remove the damsel fish once I get an octopus) and live rock. The tank has been running for a little over two months and I was wondering what would be the best way to arrange the live rock?


Certified Ceph Head For Life
Staff member
Sep 4, 2006
Gainesville, GA
That's a good conversation starter and I hope we get several different answers along with the because ... part.

I'll contribute what I do and why but I won't claim "best". I will claim somewhat successful.

I try to arrange my octo tank rockwork to provide multiple dens for differently sized animals (you don't know what animals you will be keeping nor the age when they arrive. Keep in mind their short lifespans and know you will be designing around numerous animals, not just one). A suitable den most animals would be a cave type opening with two entrances (of the animals I have kept only the the dwarf O. mercatoris sought a den with only one opening. Virtually all others would have nothing to do with a single door). Keep in mind as you stack that some octos like to use the bottom of the tank where others want to be slightly above the bottom (again the mercs were identifiable in that they preferred dens above the floor at all times where the larger species ultimately chose the bottom of the tank and removed the sandy substrate). What this amounts to is placing the bottom rocks so that you have maybe a 3" gap between them where you want a bottom den then making a cave with another opening (it can be smaller and it can be the back side of the tank if you don't push the rock against it). I like to use rocks that have some kind of point that can touch each other and support the next layer but leave a nice sized gap where the points meet. Once you have a floor level cubby, stack the next layer so that there is a second opening but provides a stable roof.

With my hex tanks, I try to center the rocks, building dens upward leaving as much space as I can manage on all but the back side. My 45 hex has its main den right in the center and it is quite large but this is difficult to accomplish without gluing or really large rocks. Centering the rocks with dens built in the rock pile seems to give them lots of climbing room both in and out of the rocks vs trying to create some kind of U to shadow the walls. Often they will hide in the back pockets of my 45 when they are first introduced but the large center den is always taken eventually.

One huge disadvantage of the hex tanks is photography. I found one picture that more or less shows the sand around the rockwork (it is not as deep as it looks as there is a plate underneath most of it and only the edges are deep). The whole rock pile is honey combed with dens but the rocks were glued. The glue has finally given up and with Diego's help the structure is not as well designed as originally placed but the underground cavern still works well.



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