Beginner question about species choice (hummelincki)

[TMoct]

Hi folks,

I am just now setting up my 75 gal tank for a future octo-inhabitant. (Actually I'm just having the stand built, then will install the tank and start cycling it). I'll make a journal when I have something to photograph, and I hope to be ready for an octopus in early summer.

I would like a little advice on O. Hummelincki. I am leaning towards that species because it seems to do well in captivity, it is around the right size, it is diurnal, and it lives in warmer water. (I would *much* prefer to not get a chiller, since I have had trouble with them in the past in my reef tanks, but I will if I have to.) I absolutely love Bimacs, but I'm worried about water temperature. Both bimac and hummelincki seem to be beautiful and personable, from what I can tell.

For those with experience, am I correct in my assessment so far? Also, are there particular suppliers that regularly carry Hummelincki? (Unfortunately there is not a section on these guys in the Dunlop & King book.)

Any advice is much appreciated!

TMoct

 

[DWhatley]

TMoct!
Please consider journaling your tank build out in our Tank Talk forum.

Your assumptions about O. hummelincki are on target. One other difference between O. hummelincki and O. bimaculoides is lifespan. In recent times we have seen the O. bimaculoides can live close to three years if kept in 65-68 degree water, 18 months (ish) at 70 but O. hummelincki have been kept for only 7-8 months (guessing about 12 months of age but being small egged, we don't see them as young). Wild caught females seem to brood very soon after being introduced to the tank. We don't know if the change of environment has an impact or if they are just easier to catch just before brooding.

Next, there is the issue of sourcing. I don't believe I have ever seen O. hummelincki advertised by name. The closest we see is Caribbean Bimac (which is not a species). I have been lucky to acquire a couple from the Keys over the years but, prior to the earthquake, most came from Haiti. Since the earthquake, we have not seen many.

As a second choice, you might consider O. briareus. They are plentiful, Caribbean, relatively hardy and personable. However, they are not diurnal. Most will learn a 6:00 supper time but they are still more active at night than during the day. We have had a couple that would spend most of their time out and about from 6:00 PM - 11:00 PM but most are active after 11:00 (but will be out for maybe an hour at an earlier feeding time) or early in the AM. Lately, we have seen quite a few younger animals available and age is always a concern with wild caught animals with short lifespans. However, O. briareus is quite shy until somewhere between 4 and 5 months (and I think this is true of other species but I have had more O. briareus than others this young).

From the Indonesia (usually through Live Aquaria but there are others as well) we see different Abdopus species and the aculeatus makes a nice diurnal animal but they are often older and don't live long. The other frequent Indonesian is an unidentified smallish macropus that is delightful but fully nocturnal.

Unfortunately, it is rare that you can qualify species and age for any on-line purchase. More and more local pet stores (not the major chains) are seeing Caribbean octos available that they can order. Most of these have been O. briareus. When I know the supplier, I will post it in the List of our Octopuses stickies and if I have a link, am adding that to this year's list. Also watch the octopus availability thread as members will post findings there.

In the meantime, use the list of our octopuses posts (I have consolidated prior years into one thread) to look at the different journals on different species kept. The lists from 2008 - 2013 have links to the journals for each of the animals listed.

 

[TMoct]

Thanks for all the info. Maybe I'll need to get a chiller for a bimac after all... Once I get the tank set up, I'll see if I can cool the water sufficiently with a fan.

With the discussion of O. briareus, I now have a follow-up question about nocturnal species. What exactly does "nocturnal" mean in a captive setting? In other words, how does an octopus react to the combination (often staggered) of natural and artificial light? As you might imagine, I am less interested in keeping an octo that I barely see. I'm just trying to figure out what happens in the evening and early morning when the sun is down but the house (and possibly tank) are lit.

 

[DWhatley]

We classify the octopuses in three ways according to their natural hunting behavior.

Diurnal animals hunt mostly by day. We have seen some variance in behavior even for bimaculoides and you may have seen keepers questioning the hunting times of their animals. I have only kept a few really, really young animals and most have been O. briareus but I am lead to believe that very young diurnals exhibit a nocturnal behavior at least in a tank environment. Since they are often found under rocks this encourages my thinking that the young hunt often at night. Commonly kept diurnals are A. aculeatus, O. bimaculoides and O. hummelincki. IME, Of the three O. hummelincki is the most diurnal and almost never comes out at night. One of mine (Octane) would pace nervously after lights out if 1) the night light suffered a power outage and reset to white instead of the normal red or 2) if I ran the washing machine at night, causing vibrations (it was on the other side of the tank wall) during its high spin cycle. When the situations were corrected he immediately went "back to sleep". My one bimac was far less active during the day than any of my hummelinckis. I have only limited experience with A. aculeatus and none for a long period but there are several notes in the journals asking about them being noctural.

Crepuscular might be used for many octos. It classifies them as hunting early evening and early morning and you will likely see this in an aquarium environment even it this is not common in the field. O. briareus and O. vulgaris assume this classification. IME O. briareus fits this in many cases and is not hard to feed at 6:00 but may or may not extend its active time between 6:00 and 11:00. It is also an animal that can be taught to eat early in the AM but few keepers have a schedule that would make this desirable.

Octos classified as nocturnal will not be seen during the day except at the very end of their lives (personal observation). I think that their eyes cannot adjust to the lighting but in senescence they start losing their sight. The Caribbean dwarf, O. mercatoris and the Indonesian unknown Macropus fall in this category. Where O. mercatoris can be fed easily at 11:00 and sometimes as early as 9:00 if the sun is down or there are no windows, the macropus does not adapt to any light and is most active at 3:00 AM. Some keepers have had better luck feeding the macropus a earlier but both mine had no interest in being out, even to eat, until the wee hours. Great little animals and very interactive but not during most human hours.

Several people have wondered about artificially creating a night environment and I cannot fathom that this would not work since the Indonesians change time zone radically and are still nocturnal. The problem with experimenting is that most rooms have windows and the ambient light is controlled by the sun. Additionally, keeping a tank in a daylight dark room is not very practical for enjoyment.

Artificial lighting needs for an octopus are non-existent as they would likely be happiest with just ambient light. However, anything else you want to keep (this is minimized greatly by the primary occupant) usually requires additional lighting. There are numerous discussions about high light and cuttlefish and the most accepted thought is that even metal halides are acceptable. I would disagree when it comes to octos. I don't believe it will hurt them but I do believe you will see less of them if you use bright daylight lighting. Even with my compacts at the back of the tank I notice that the eyes are not fully opened until these lights are turned off.

For night lighting for any octopus, I recommend using red and not blue lights. There is evidence that blue night lights may appear brighter than white light to the octopus where red light is close to invisible and I have used fairly healthy red lighting with O. mercatoris (great for viewing, lousy for photography) very successfully. I keep a section of all three octo tanks lit 24/7 with red light and with a full nocturnal will light the entire tank that way. Interestingly, I have found that young O. briareus will choose the red side for a den but will migrate to the "dark side" after they are fully mature. Dools recently tried an experiment with Waldo and switched his red light to blue. His Macropus did react to the blue and returned to its den. There have been others that use blue and seem to have success with it but I highly recommend at least starting with red.

 

[DWhatley]

One thing I did want to mention is that O. bimaculoides are very hard to acquire if you cannot catch one yourself. On a rare occasion we see someone with hatchlings (the ideal way to acquire one but they don't ship well until they are a few months old) but the are illegal to harvest for sale in California (you can use them for bait, eat them or keep them yourself but you cannot sell them) and most live along that coast. Stu (Coldwater Marine Aquatics) will sometimes find them but they are usually spoken for in advance. Depending upon the time of year, his time and the moon, Joe-Ceph has been able to help a few members legally obtain one.

Unless you can regulate the room with air conditioning or the tank sits in a basement or you live in a very cool climate, it is unlikely you will be able to maintain temperatures for a bimac without a chiller.

 

[TMoct]

Thanks, again, for the advice.

It sounds like my best bet forward is to go ahead and get the chiller, so I'll have complete control over the water temperature and will be prepared for a variety of species. (Any recommendations on a quiet one? People seem to like the Teco SeaChill).

Further, it sounds like I should not be overly picky about species, given their normal lifespan and their unreliable availability. Over the years I will have many specimens, of a variety of species.

By the way, this kind of information is exactly why the Tonmo forums are so valuable -- this kind of current hands-on info just isn't available anywhere else (that I have found).

Cheers,
TMoct

 

[DWhatley]

Further, it sounds like I should not be overly picky about species, given their normal lifespan and their unreliable availability. Over the years I will have many specimens, of a variety of species.

This is something I try to remember to stress when people are starting new tanks. You will take more time preparing for your first octopus than it will be with you (with a very few exceptions) so creating an environment should be the primary focus. Additionally, we do allow octo keepers to temporarily go to the cuttle-side on occasion . If you create an octo environment, you can easily try cuttlefish in the tank as some point should they interest you. A 75 is a great size for most options and if you limit your "other" things will bring years of cephy enjoyment.

I have often read that the Teco is a great brand but have never owned one. ATM, my chillers are off and won't likely be returned to service (I do still pump through both of them to keep the insides from becoming stale and, well, you never know ... ). However, they are lower end chillers and I don't have a lot of experience to pass on.