[Octopus]: Davy Jones - O. hummelincki

LOL. I see you noticed I left senescence off the list of possible problems...

I'll try to pick up some different foods tomorrow. We feed the GPO at the National Aquarium smelt among other things. Do you think this would be suitable for this type of octopus? The local grocery store has smelt available. Or should I spring for something like tuna? I can look into fiddlers too. Unfortunately I don't have any local fish stores near me. I'll see if Petco has any fiddlers (I don't recall ever seeing any on the occasions I've been there though).

I know this might seem like denial, but I can't help but think it's way too early for this to be the end. Is size any indicator of age? Davy appears to be a lot smaller than ET. Does O. hummelincki only usually live for a year? I see you've had ET since May according to your thread. Do you expect it'll be the end for him soon too?
Octopuses can vary greatly in size even within a group of siblings and O. hummelincki may have the largest range recorded during a study (somewhere there is a paper that did work with them and recorded a huge variation -- I will try to see if I marked it and link with an edit). Octane (sadly most of the photo links no longer function and were added before the forum had large picture upload capabilities) had a mantle almost as large as my (female) fist and Maya was dwarf sized but most have been full grown about ET's size.

In general (never absolutes with octos) an octopus entering the last week of life will fail to color much and takes on a grayish white skin color. Post brood females will seem to have difficulty controlling their floppy mantle. Sometimes males will also show this lack of body coordination. All do seem to stop eating but they can slow their eating to very little and live more than a month or stop and be dead in 2 days. On average, I would say that a 2 week period of decline would be what to expect.

Deny away and continue to encourage feeding. They do seem to go through behavioral changes and will often change their eating habits during these periods. Sexual maturation seems to be one of those times and includes the transition from rapid growth to a much slower paced cycle. Never assume senescence until all water quality is monitored (high nitrites in particular will often give the appearance of senescence and are just as lethal if not quickly addressed).

Feel free to try anything from your local fresh seafood counter (ie not canned or cooked). Don't buy in quantity though as sometimes an initial offering will seem happily accepted but then never eaten again. Scallops seem to fit this scenario often. If a food item is rejected, don't hesitate to try it again in a week or two and try varying the size of the portions. I swore that O. mercatoris would not eat table shrimp until one day Neal (spouse) offered one of our a small piece, not knowing she would not eat it. Much to my surprise, she was just fine with consuming it as long as the size was to her liking. All other mercs after her also learned to eat it when offered a eye size.

Edit: Here is a link to links to several papers on O. hummelincki. Open the first link (use the "pdf link" and scroll down to about page 10 to see the sizes recorded. The whole paper is worth skimming and you will likely enjoy some of the other material collected as well.
Thanks a lot for the reply @DWhatley. I'll give a few things a shot and see what happens.

Question on nitrates, this guide says levels between 50 and 100 ppm apparently have no effect on octopuses. Is this actually correct? This seems alarmingly high coming from a reef-keeping background. What do you personally target for nitrates for your cephalopod tanks? Either way, I'll give nitrates a test this evening. I haven't tested in a few weeks, but my water change have thus far been keeping them in check.

I'd be really surprised if salinity is off, but I'll check. I mix up Instant Ocean in 44 gallon batches. I basically fill a 44 gallon Brute with deionized water, add an entire bag of Instant Ocean, and check conductivity after a few days. I adjust to 53.0 mS/cm and it usually stays there until I use the whole can. The can stays sealed and experiences very little, if any, evaporation.
As far as we can tell, nitrate levels don't affect octopuses and are often very high in aquariums because of the quantity and type of raw food they eat. I do fight to keep mine below 60 with water changes, reducing or removing the bottom substrate (ET has a bare bottom tank) and using a small deep sand bed in the original filtration compartment of one of my tanks (I keep meaning to add one to the other but have not set up the bucket arrangement I have mentally configured). I have not tested ET's tank in a long time and your post reminds me I need to see if removing the sand and now having an aged DSB have helped. There is, of course, no harm in having low nitrates except if it is done by water changes that change the other (salinity and PH) stabilizing parameters.

I suggest the salinity check only because mine was way low last week in all my tanks and I have not changed the way I mix for years (two 20 gallon containers that mix for at least a week before use). I suspect this last batch of salt (Instant Ocean) may be the culprit.
Thanks for all the help @DWhatley. I tried smelt and he has no interest. I tried a 40% water change to see if it was something in the water, but I haven't seen any improvement. I tested nitrates and they were just about 50 ppm on the Salifert test kit. After the water change they're probably closer to 25 ppm.

I think this might be the end. My supervisor at the Aquarium said that octopuses sometimes behave like they're senile when they've entered senescence. Davy seems to behaving somewhat this way. He's holding his arms at odd angles and his movements seem rather uncoordinated.



If you think it's worth trying a few more foods, I can do so. It seems like he doesn't have any interest in the stuff I was offering, so I don't know how much loading up on other foods will help.
Davy died last night. I'm almost glad, he was looking really rough and was having a really hard time breathing. I didn't want him to suffer for too long and I don't think he did.

Thanks @Maggie, @tonmo and @Carmen22. He was really a cool little guy, and though the experience was short, it was definitely enlightening and I learned a lot.
You are a quality ceph-keeper, @chipmunkofdoom2 - hope you are back at it soon. Thank you for sharing your learnings with the community - this is a tough trade - and as long as there are octos being sold and kept, it's important that we continue to share experiences and knowledge to better our collective expertise! Thanks!
So sad to hear Davy lived for so short a time. Yes, it is best on keepers when senescence appears short but some theories think it starts much earlier than we observe. The lack of coordination paired with the extended lack of food interest is usually what we notice in the end. I have had some pass while still displaying full color, however, most also show a lack of ability to fully or change or only hold patterning for a few seconds before reverting to a greyish white. Early on, Neal suggested that I either accept the deaths or not keep them. Clearly I have chosen to enjoy their short lives and accept that we don't have a way to extend them.
Thanks @DWhatley. Having your support through this short journey was really valuable, and I appreciate it.

I was wondering exactly what you voiced in your last sentence. I enjoyed having Davy, but he really didn't live as long as I would have hoped. I think given a few months I might be ready to try again.

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