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question about bimacs

Oct 9, 2006
hey everyone,
I'm new around here, I've cruised the forum for a while as I was looking into cuttles for a while, but I'm planning a future tank and Im 99.99% sure i want to try out a bimac. I have a few years of reef experience, and i've doen plenty of reading so i'm pretty confident that I will do alright with one. anyways, my question was about aquiring one:
I know bimacs are available online, but from what I've read they have a large range. I see some that are kept at trpoical temps, but I know for a fact that I've seen one in cooler waters ~65-70 F
Are they all the same species? are people just confused? or am i just missing something?

I was also wondering how easy....well, how practical is it to collect one myself? I live in S. California and a collecting license isnt a problem, and I have played with them in the tidepools before (dont know how I would ever get one OUT but it was entertaining). Do you think it would be better to get one myself or risk ordering one from an online source?
I forgot to mention, I also want to design a special aquarium. I dont want the typical rectangle, any ideas? It will probably go in a corner so i was thinking maybe an L shape? or maybe two tanks connected by tubes/pipes? Im open to opinions, and if anyone has pics of unique tank shapes please post.
Hi and welcome to TONMO.com!:welcome:

We have had several people in southern California collect their own bimacs, and it seemed to work out fine.

Bimacs live in cooler water but tolerate wamer temperatures to a degree. We advise keeping the tank temperature in the low seventies, if not lower.

:welcome: to TONMO!

One thing to note about collecting bimacs is that there are 2 species, bimaculatus and bimaculoides, which are very similar in most regards and live in the same areas of California, but bimaculatus is a small-egged species while bimaculoides has large eggs where the young have a much greater chance of surviving in tanks. The requirements for keeping them are very similar, so if you're not interested in breeding them, that may not be important, but it's worth noting.

Also, California bans the collection of these octos for sale to the pet industry, so to legally collect one for yourself, you need to do it with a sport fishing license.
Ya i've read about the licenses, So i know I have to get one before I go collecting. I'm not just going to walk up to the tidepools with a 5g bucket...and then have a fun time explaining to the patrol exatly what I'm doing with an octo in it :wink: . I have no intention of breeding them, at least not anytime soon, but are there any distinguishing characteristics between the two? other than the egg size.
Also, anyone have any tricks for catching one? I havent been able to get them completely away from the rocks before, then again I wasnt trying to cathc them then either. what size should I aim for so I get a decently young one? When do they breed anyways? I wouldnt really want to pull out a gravid female.
To the original question of temperature: cooler is better. I don't think the range of either bimac species extends into tropical waters. I believe the water temperature in the area ranges from 60-70 degrees F (some of you locals might correct me?) and so its best to try and replicate this in the aquarium. You can keep the animal at room temperature, but its metabolism will be faster and its lifespan shorter.

Good luck

well, my original plans were for a reef with extensive lighting, so a chiller was already in the picture. Now I'll just end up saving money since I wont be needing those halides huh?

Now, I have an idea for the tank, still in very early stages of development but tell me what you think:
going to make an L shaped tank that fits into a room corner. I originally though of connecting smaller tanks with acrylic tubes or pipes, but thought it was too risky to make myself as any leaks, broken seam, or unwanted syphons would be very very bad...
But I still wanted different chambers to entertain both me and my 8-armed friend. So i am thinking of putting barriers in the tank, much like sump baffles but from top to bottom, and just cuting out 1 or 2 holes in each wall so that the octo has to contort to cross. Or maybe instead of plain holes I can put acrylic tubes through those same holes to better observe the shape shifting? I was also planning to change the environment of each chamber, I mean different type of food would be available (or fed) in each chamber and each would have a different theme 1st might be all rocky like and partially dry like tidal zone, second like a deeper area with less rock more open sand, and maybe the 3rd be more refugium style wth lots of plants. i know the tidal zone might be hard to pull off, but maybe I can work something out. What do you think?

lastly (sorry i know this is long), how important is height in an octo tank? i know system volume should be >50g, but do dimensions make a difference?
It might be really interesting to do the inside connecting tube idea with the section contining the tube as a miracle mud planted refugium.

A word of caution though, you will have to clean the inside and outside of that tube pretty regularly to keep it clear so be sure you have easy access to the openings as well as the outside. You may even want to size it (or them :sagrin: ) directly relational to a cleaning brush (i.e. find an acrylic safe brush and size the tube to be easily cleaned in a couple of passes). If you can find a glass cylinder (or two or three) they would scratch less and an absolute seal is not necessary with your intank design.

Just some thoughts - keep your progress posted!
ya i already thought of the problem of keeping them clean. those tube brushes would be a must, and some kind of sponge would be needed to keep the outside clear. I was thinking the tubes should go right about the substrate line give or take an inch. Each septa (check out these technical terms) would have at least two tubes connecting it to the next chamber. After talking to my friend, this is what I got:

Looking to make a 3 or 4 foot tank, basically a 50g but shorter than average. the first chamber from the left will be tidepool themed, with some exposed rock and sand ( i think i even found a way to create tides but I'll explain later) and the menu there will most likely be locally collected shore crabs and snails. the next chamber will be refugium styled, many plants and finer grained sand, some rocks too. The last chamber will look more off-shore. The background color will be darker and there will be less rock and more open sand. to compensate for the lack of hiding rock i will put in glass bottles, jars, and other "debris" to simulate stuff you might actually see at the bottom of a harbor....that and i think it would be entertaining to see an octopus sqeeze through the neck of a coke bottle to get at a shrimp or crab. Sound like a good idea?? personally I think its the best plan ever....but we'll see if I have the skill to make this thing. Wont be able to actually build until late september when I move into my appartment, but I'll post some drawings or somthin if I get it layed out on paper.
sorry forgot to mention the menu's of the other 2 sections. the fuge wil have saltwater feeder shrimp, and i was thinking the off shore one could have clams or somthin....any feeder fish that are suitable?
Why put the tubes near the bottom? I don't think there would be any octo advantage, it would be much harder to clean and you would not get the best viewing. The tube doesn't need to be very large in diameter but it does need to be full submersed.

In stead of "junk" in the third chamber, why not a sunken ship (plastic of course and NO paint). Norgebyblood made a castle from Dublo blocks that were well received by Schlemm http://www.tonmo.com/forums/showthread.php?t=9703&highlight=Schlemm and Leggos has all kinds of creative stuff (a friend brought me a Leggo octopus the other day :biggrin2:
Well, i havent seen any, but i dont really think a plastic ship with no paint would look very good? Can I use the kind commercially available for aquariums or do those corrode too? I do like the sunken ship idea though. Lego's are easy, but im going for a more realistic look, you know? Guess i should look aroud for some toy ships, it would make a great deep ocean scene.


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