Dwarf cuttlefish tank

[EMeyer]

Finally got around to taking some video of my dwarf cuttlefish and thought I'd share.

I've had the tank running about 6 months, the cuttlefish themselves are about 3 months old now. The display tank is a 29 gal with macroalgae and soft corals. It drains to a 20 long sump + macroalgal refugium, and the return pump also feeds a 20 long shrimp refugium. I have very light skimming (a skimmer from an old biocube) but all this live rock and macroalgae keeps the nutrients in check so far. /crosses fingers

Here are pictures of the cuttlefish a few days after hatching. (eggs from bluezooaquatics) Currently I have 4 of these, plan to thin down to 3 as they grow.

Here they are now, at about 3 months old

They share the tank with macro algae, soft corals, and the few inverts they wont eat

A video of the cuttlefish from a week or so ago

A video of the cuttlefish feeding, today

Here are the display tank, shrimp refugium, and sump/macro refugium. Return pump in sump feeds both the DT and shrimp tanks, and these both drain back to macro refrugium/sump.

 

[Flashy Fins]

So cool!  Your rockscape looks really nice, too. 

[Sasquatch]

That's some great camera work.. next pic of the month. Cuttlefish.. you win

[Nancymacc]

Its like an aquatic chameleon the way it catches prey!! that's awesome.

[Stugots]

Wow. Very cool. Thanks for sharing!  Nice slo-mo in the feeding vid, too. 

[EMeyer]

On 6/10/2017 at 7:35 PM, EMeyer said:

 

"the few inverts they wont eat"

"inverts cuttlefish will tolerate" .... turns out thats right up there with "hold my beer and watch this". That crab was about 4x the size of the cuttlefish but that just means he took longer to eat.

Heres an updated video of some color changing and staring down the camera. 

 

Edited June 20, 2017 by EMeyer

[Aznbala]

Sweet videos. Always loved cuttlefish. I didn't think they lived very long

[Reefer Ryan]

They are so interesting to watch, 

[EMeyer]

Update time! No pics close at hand but what a story. I'll fill in some pics and vids later. Since my last update:

First, they reached reproductive maturity and things got complicated. Turns out I had 3 males and one female left. Which was exactly 2 males too many. One disappeared completely, its unclear who ate him but I only found his beak. Not even the cuttlebone! Another weak male I rescued after he took a beating, but he died shortly after from his wounds. 

After that, the strong male and only female settled down to domestic tranquility and behaved like a strongly pair-bonded couple. They had funny interactions during feeding and were more or less attached at the hip... err, mantle? They mated constantly, and produced 11 batches of eggs over the next couple months. Sadly, I was unable to get any to hatch. Not sure what the issue was, since I have good luck with purchased eggs. I will note that none of these homegrown eggs plumped up as much as the purchased ones... perhaps there were fertility issues?

In any case, what came next was a surprise.

It all started with a sea urchin. This MFer was constantly messing up the tank, and one Saturday morning he was up to his tricks tearing up mushroom and zoas. So I stuck my hand in the tank (what comes next is never good) to grab the urchin and scared the female cuttle. She darted across the tank... face first into the anemone.

This is nominally Calliactis polypus, the symbiotic anemone found on hermit crabs. Funny enough, the remaining male had long ago eaten the hermit crab himself but his anemones remained...

I immediately brushed her out of the anemone, within seconds, but her fate was sealed. She suffered from intense poisoning over the next 4+ hours, and eventually succumbed. It seemed like a neurotoxin (she basically acted really really drunk) so I held out hope she might recover in my hospital tank but alas, it was too much. Powerful sting, that little anemone. RIP.

Minutes after I removed her from the tank her mate swam to the top, obviously looking for her. That night he refused to eat. And for the next 2 days. On the third day I bought some live food ( a rare treat, I'd had them on frozen krill for months)... but he had passed on. He floated there in his hiding spot, still neutrally buoyant, but dead.

Its an anecdote, with no control. But these animals have intense behavior and personality that I would rate nearly on par with dogs. I watched the behavior and it truly looked like a pair bond followed by death of a broken heart.

There is biological precedent for this but I am unaware of another example in invertebrates. So call me cold hearted or easily distracted by shiny hypotheses, but we are gonna actually do the experiment to see if this is a thing. Stay tuned.

In the meantime, I couldnt resist and bought some more eggs which promptly hatched and have just eaten their first meal. pics to come. But I figured the story was worth sharing on its own

Edited September 30, 2017 by EMeyer

[albertareef]

Sorry to hear about your mated pair but fascinating story/behavior.  Thanks for sharing.... looking forward to hearing how things turn out with the second batch. 

[TheClark]

Amazing experience, thanks for sharing.  That would be a fun thing to try some day...  Sorry for your losses...

[EMeyer]

Update time.

A few months ago I got some new eggs to restock the cuttlefish tank. This round was not as easy as the first; I had poor hatch and mortality rates this time so I had to order two batches of eggs then a couple hatchlings.

But at last, I once again have two cuttlefish in the display tank.

One of the cuttlefish I hatched from an egg in this round is nearing adult size. Here are a few video clips of her (I hope its a her) feeding. These are the first videos documenting her feeding in the display tank, not the best videos. The video quality is not great but check out her use of camouflage in hunting behavior at the end, pretty cool.

Next steps: training them onto frozen food. So far they show no interest. 

Also, the second cuttlefish (purchased later as a hatchling) is still smaller but I hope he turns out to be a male. In my first batch, the males were more adventurous and aggressive in exploring the tank and feeding, while the female held back and only fed after the males had fed. In this second batch, the larger cuttle is cautious and I am hoping shes a female. The smaller one is a bit more adventurous, hopefully he turns out to be a male. We've already seen how multiple males in one tank works so fingers crossed... 

 

Edited January 13, 2018 by EMeyer

[youcallmenny]

What a great thread!  Thank you for sharing.  

[Emerald525]

Thanks for sharing. I had missed some of the prior updates but that was a fascinating and sad story.

[EMeyer]

OK. Some new information...

I've been raising the larger cuttlefish (hatched from an egg) and the smaller one (bought as juvenile from bluezoo) together in the display tank. They didnt show the coordinated feeding behavior or swim together like my last batch. But they did rest in close proximity to each other and the big one never showed any aggression toward the little one. Keep in mind, the primary cause of the difference in size was simply age. The big one was hatched from an egg about a month before I bought the then newly-hatched juvenile.

As you might expect, the larger one has been getting more of the food. Several days ago, I watched as she ate the first two shrimp without letting the little guy get any. So I added two more shrimp and she ate them both in rapid succession. Now I was worried, and this supported my growing fears that the little guy was not getting enough food. So I moved him to my hospital tank (a secondary refugium connected to the display tank and sump) and gave him a shrimp. He showed no interest... and died 4 hours later.

The next day, the bigger cuttlefish, left alone in the display tank, showed no interest in live food and also died later that day.

The cuttles were about 5 and 6 months of age (less than the maximum lifespan of 1-1.5 years) and even the largest was smaller than the expected maximum size. Lifespan is dependent on temperature in these animals so I keep them relatively cool (25-26°C). I also did not see any of the prolonged senescence that's been described in these animal in old age (cataracts, loss of feeding abilities, reduced swimming performance). So I find it unlikely they died of old age. 

Since these animals never showed any strong evidence of pair bonded behavior this casts doubt on my previous hypothesis (death of a broken heart). I see several possibilities. 

1. Some change in water chemistry killed both animals. Nitrates were undetectable as always (there is a ton of macroalgae in the system), and Ca and Alk were normal (>400 and ~9 respectively). I had recently corrected a salinity deviation (from just above 40 to 35 ppt). It is possible that this stressed both animals and they died from it. But I dropped salinity slowly over a period of 3 days and nothing else died, including several echinoderms known to be highly sensitive to salinity fluctuations. So I am skeptical salinity did it. Perhaps some other, unknown and untested change in water chemistry?

2. A disease infected them both and they died from its effects. Impossible to rule out. I think literally nothing is known about cuttlefish pathogens.

3. Some problem with a batch of food killed them both. I buy grass shrimp in batches from local pet stores who receive them in weekly shipments from their wholesalers. Perhaps one of these batches was bad in some way, e.g. some medication given to the shrimp or a pathogen carried by them.

4. Perhaps the animals were in fact pair bonded like I hypothesized with the first batch (the previous story, above). They spent most of their time out of sight in caves in the rock, and I only observed them for minutes to an hour each day. Perhaps the same thing happened as before... or perhaps the previous story was caused by one of the alternative explanations above.

Lacking funding to pursue this question in a systematic way, all I can do is incrementally improve. I will work next on growing my own food source as much as possible. I am gonna take a break for a bit from cuttles and leave it as a feather duster and echinoderm tank for now... but I'll come back at it with another batch and try again, with homegrown food. I will also take monthly water samples and preserve these to later testing in case another mortality even occurs. 

Such interesting animals. But there are clearly a few more details to work out for keeping them in captivity. 

Has anyone reading this ever kept dwarf cuttlefish? If so, have you ever observed mortality like I've described here?

[albertareef]

Sorry to hear you lost them - better luck with the next go around.  Very frustrating when you can't put your finger on what went wrong.