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Mercatoris care tips

Joined
Aug 9, 2015
Messages
71
Hi, I'm a long time reader and a brand new member, and I'm wondering about the water perameters for a mercatoris ( caribbean dwarf octopus ). Also, if you could give me a good feeding schedule that whould be great. BTW this is my first octo and it arrives in a week or two; also, I've been reading up A LOT:read:
 

DWhatley

Kraken
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Sep 4, 2006
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We have a special :biggrin2: collection of post for beginners (also look at the articles) in the stickies of the Octopus Care section (Posts with Infor for New Octopus Keepers) that should be helpful

IME Mercs seem to do best in a 15-30 gallon tank with lots of hiding places. I have found that if you will place a collection (various sized openings recommended) giant purple barnacles (link is for reference only, but eBay is not a bad place to find them) about 1/3 of the way up the tank (either by finding a larger collection that can sit on the bottom or by embedding the cluster in the liverock), they will often choose one for a den and can be seen (this seems to be particularly true of the females who will establish one as a den for her life, males tend to move to different dens every couple of weeks - sometimes choosing the barnacles, sometimes hiding in the live rock). They MUST have a dark place for daytime denning as they are nocturnal. Often they can be trained to expect food between 9:00 and 11:00 PM (lights off at 7:00 ish for the earlier attempt) but don't expect them to be active before 11:00 PM. Red lighting (NOT so with blue moonlight) is easily accepted but I recommend leaving it on all night (or 24/7) so that there is never a fully dark time. Ambient light for daytime is fine but most non-halide lighting should not be a problem as long as they have a totally dark place to stay in the daytime. Temperatures between 75 F and 79 F are desired.

Freshly killed or damaged shore shrimp (only the young seem to be able to catch healthy shore shrimp) or small live fiddler or othe small crabs (pretty much a universal octo food - disable or remove the large male claw on fiddlers and all claws on other crabs) are usually accepted. We have found that once they are eating well, pea sized piece of thawed table shrimp may be accepted when offered on a feeding stick (or bamboo skewer).

You can search our Journals (use the title check box and the term mercatoris) for others experiences (including some of mine :biggrin2:). Please consider journaling your experience.
 
Joined
Aug 9, 2015
Messages
71
So to recap, blue lighting doesent work like red lighting, remove claws,(Thats gonna be hard), barnacles of any dark place is good for hiding, they might accept shrimp, Don't leave the tank COMPLETLY dark and ambient lighting is fine for the day (the typical white lighting right?) but I have one question, can you USE blue lighting, or would that stress it out?:confused2:
 

DWhatley

Kraken
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Sep 4, 2006
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You can use blue in the daytime (as in an actinic) but NOT for night lighting. From what we understand of their vision, blue is actually brighter than white where red is a spectrum they don't see (or don't see well) and is similar (though they can detect what I have used) to total darkness but allows you to view them. No light at all at night is fine but you will not be able to see them.

Removing crab claws is simple. I try to break off the tip of the smaller part of the large claw on fiddlers but more often than not they will shed the claw before I can remove the tip. I don't usually remove the smaller claws or those on the females unless they are large but other crabs and the male fiddler's "fiddle" claw can cause skin damage (to both you and the octo :biggrin2:)
 
Joined
Aug 9, 2015
Messages
71
Huh, thats really interesting. I didnt know dark blue was brighter. So I guess its better if I use white? Or I could use the inbetween setting. I guess it is easy to declaw fiddlers.But is it okay to leave the claws on Emerald Crabs? better yet, can I feed them Emerald Crabs? And to see them better in the tank I could just turn on the roomlight when Im there in the room to see it.
 

DWhatley

Kraken
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Joined
Sep 4, 2006
Messages
20,856
White, white-actinic blue is fine for daytime (it will be sleeping). For viewing at night, when it is active, use red (no lighting will be frustrating and you won't see much, room lights should be off. There are a number of ways to set up a red light. One is rigging a red bulb in a light fixture (sometimes I use a shop lamp). Another is to put high temp red velum over the in front of the light fixture (must be pretty close and should not leak white light - I have used an outdoor light with velum as well as heavily painting the outdoor light lens with red paint.) There are also some aquarium "moon lights" that can change color and can be programmed to be red. There is a sticky in the Tank Talk forum with links to some of the red light finds members have located.
 

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