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new to the octo


Jan 26, 2009
hello all,
i have just purchased my first octpus was looking for some advice and maybe a few questions answered.

i know many people worry about octo owners not being "experts" but i would surely consider myself a saltwater expert. i have been breeding fish for 13 years and have been raising corals for nearly 5 years. i have a buddy that owns a pet shop and recieved a dwarf octopus, from comparing him to pictures on this site, i would call him an o. mercatoris.

he originally came in a medium size cricket cage that i sat in my frag tank until his tank was completely ready, but this did not work out as planned. i have some banggia cardinals in the tank and the instantly started poking at the cage and trying to get to the octo and then he inked while trying to get to the other side so i had to act fast. i set up a 15 g hex with an under gravek filter and used the substrate from my reef tank and the live from it and the water from it and waited about an hour until i put him in and everything is doing just fine and the tank is at 78 degrees.

i ordered some ghost shrimp and some fiddler crabs for food but they will not be in until tomorrow so all i had to offer was a freshly hatched percula clown.... i know its unfortunate.

could you please let me know if this set up will work for him, how to tell if it is a him in the first place, if i can have more than one, how to trigger breeding and when to try and breed them and any other useful things i might want to know...

thank you
just going by what i read from other posts, 78 degrees is a little warm. also, they will eat hermit crabs and mine has eaten a snail or two. so im sure you can find something to feed it.
There have been no recent journaled successes breeding wild caught octos. Greg and I have successfully bred mercatoris siblings from wild caught females and there is nothing special to encouraging breeding when both sexes are living together:

Beluga's babies = Varys' grandbabies (O. mercatoris)
[Octopus Eggs]: - Trappers Grandchildren - Tank Bred Mercatoris

We have two new members keeping their first mercs and much of your housing questions are answered in their threads:

Mercatoris Pair Journal
my octo just got here !

K0mpresd had already beaten me to recommending that you lower the temp :cool2:. You will want to add red lighting to view it at night.

Sexing is difficult with the mercs (as you will learn from Gregs thread) but, when fully mature, the males will usually carry their third right arm (clockwise) curled most of the time and will not use it for climbing and searching for food. Sometimes you can identify enlarged suckers on one or more of the front arms. If the octopus changes its habits, closes itself in a single den and refuses to eat, it is likely a brooding female.

Your tank is not mature and is small. Both conditions require large weekly water changes and close monitoring of the water. Be sure your salinity is full seawater (1.025 - 1.026) and not the typical lowered salt content for a reef. If it is low, do your water top offs with saltwater until you reach full density. An experienced marine aquarist can house two in a 15 (20 might have been better but I use a 15 so I know it works) as long as the water is well maintained and there is very good areation.

Good luck and please start a journal for your new friend.
thanks for the reply i will for sure check out the threads. i tested everything tonight and it is all stable so im pretty sure its not going to have rough cycle since i really didnt start a new tank i jsut took a chunk of a well established tank and added new glass, if ya know what i mean. im glad i checked tonight and not tomorrow, my salt was at 1.025 and i was actually wondering if i should drop but you answered my question already. i figured i would have to do alot of water changes with such a small aquarium. it looks really smale cuz its right by my 85g reef.

also, great idea on the red lighting im going to order a bulb first thing tomorrow from work. i had another question tho, would you recomend using R/O water, i have access to 100 gallons or more a day at work so it would be no problem getting, plus its free and i dont have to buy the highly overpriced units.
alright i will bring some home tomorrow, i started a journal for the little guy, his name is stanley, ive got 4 pics on there right now if you could let me know if he is acutally a merc. thanks

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