My Experience with a Mimic Octopus Thaumoctopus mimicus

Author: Barry Wisebram

After taking home a rare mimic octopus for the first time, the author shares the many thrills and heartaches he experienced while getting to know this fascinating animal.

Excitement in the Fishroom

Concern has been raised over the possible endangered status of Thaumoctopus mimicus. As always, there is a delicate balance between our concern about harvesting such animals from the wild and our desire to perfect husbandry protocols to enable captive animals to thrive and reproduce. Certainly, only qualified aquarists should undertake keeping these cephalopods, and they should strive to discover how to raise their spawns in captivity—Eds.

After 25 years in the pet industry and 20 years in the fish business, currently as Vice President of Sales at Sun Pet Ltd. in Atlanta, Georgia (a livestock wholesale company) I find it hard to become extraordinarily excited about marine life, until…

Steve, our saltwater manager, barged into my office and interrupted my paperwork, demanding that I go to the fishroom “right now!” and refusing to explain what the commotion was. I knew something had to be out of the ordinary.

A Special Find

An amazing creature awaited me in that fishroom. Chocolate brown colorations with white stripes, horns above the eyes, and long legs undulating with every careful-yet-cautious movement. As I bent over to catch a closer glimpse of the organism, he seemed just as determined to observe me as I was to observe him. This was a creature that was first discovered in 1998—Thaumoctopus mimicus Norman & Hochberg 2005, the mimic octopus.

This is a rare specimen to come across, particularly in the aquarium trade, and here he was at Sun Pet. I knew right then and there that I had to have it. After waiting the obligatory few days so that customers could have a shot at it, I purchased the octopus and took it home. I was careful to acclimate it slowly, since octopuses can be extremely sensitive to sudden changes in water temperature and chemistry. After acclimation, I gently lowered the bag into the aquarium to allow him to venture out on his own. As he entered the tank—containing pieces of live rock, an orange sponge, and some snails—he quickly spread his legs as if stretching in all directions, and then he retreated behind the rocks.

I took the now-empty bag from the aquarium, closed the top, and did my best to ignore the tank for the rest of the evening. As I laid down that night I had images of the mimic impersonating creatures like the sea snake, sole fish, and lionfish. Unfortunately, I never would see it mimic any of these creatures.

Getting Acquainted

The next morning I ran downstairs to check on my new friend. I slowly entered the room to avoid detection and saw him in the middle of the tank pacing back and forth. The instant he noticed me he began flashing some colors through his body and then quickly sought refuge in a cave in the rocks. He had survived through acclimation and appeared awake and active the very next day. This was a great sign, especially for a sensitive mimic octopus.

The Fiddler Crab

I dropped a black fiddler crab into the tank to see how the new inhabitant would be greeted. After a short time, an arm projected from the rocks, snagged the crab, and quickly withdrew back into the cave. Awesome! Not only did the octopus appear to have acclimated well, but he also was already accepting food. This seemed contradictory to most available information regarding this animal. Most forums and articles I have read suggested that it is nearly impossible to get a mimic octopus to arrive live after being packed and shipped from Indonesia, let alone have it adjust to acclimation in two separate systems within two weeks and readily accept and digest food.

Don’t Be Shy

Several times later that day I walked by the tank hoping he would venture out to explore his new environment. I was disappointed. He did not come back out until the following morning. That afternoon I decided to feed him again. I threw in three black fiddler crabs, and as quickly as he could eat one he would grab for the next. This was going perfect! After all the feeding I decided to do a water change and clean the gravel. I siphoned most of the water and detritus out and refilled the tank with salt water that I had mixed an hour before.

Cleaning the Tank

Because the tank was so dirty to begin with and there was such a small amount of water to siphon, the tank was not exactly spotless when I was done, but at least the water was clean. I checked in on him several times during the day to see if there were any adverse reactions to the water change. I could see him looking out at me from his cave, but he didn’t come out into the open for the remainder of the day.


The next morning he was nowhere to be seen. The tank was not large, but I still could not see any sign of him at all. I headed to the office worried that I might have killed him with my massive water change the day before. As soon as I returned from the office I checked the tank again…still no sign of my octopus.

Was it possible that he could mimic a rock so well that he would be undetectable? If he had died, surely I could at least see the body. I checked around my kitchen for signs of him in case he tried to make a getaway. I looked under the papers on my desk and behind the computer next to his tank. I looked inside the filter chamber in case he decided to resemble mechanical filter floss, and still he was nowhere to be found.

Later that day I decided that I would take the opportunity to rearrange the rock in the tank so that it looked less crowded and haphazard. I began removing pieces of rock from the tank and put them in a bucket. In removing the rock I managed to stir up the detritus left in the tank to the point of not being able to see anything.

As I was feeling around for the last pieces of rock in the tank, I felt something feel me back. Could it be? There was my mimic octopus, very much alive and probably trying to figure out why I was tearing his home apart! I have read that these animals are found in silt-covered river bottoms where rivers and oceans meet, so perhaps this made him feel more at home. Nevertheless, I was thrilled to see that he was alive and well. I had not realized how much I had become attached to him. I carefully put the rocks back and did not disturb the tank for the rest of the evening.

Leaving Him Alone

Over the next few days, I brought small pieces of soft coral and polyps home and transformed his tank into a mini-reef. He seemed to settle in and become comfortable with his living arrangements. He continued to eat three or four crabs a day. He would come out when he saw me approaching and seemed as excited to see me as I was to see him. We had bonded; I would spend hours watching him flash colors and pace the tank.

Ten days after bringing him home, I left for Chicago to attend a trade show and was gone for six days. I had given him a few crabs the morning I left and decided to not have anyone feed him in my absence. Small tanks are easy to foul with overfeeding, and I tend not to trust other people with the feeding of my tanks. Fish are always better for up to a week without feeding, rather than risk the chance of someone not familiar with them over-feeding and sending the tank into an ammonia spike and subsequent crash.

Where Did He Go?

When I returned from Chicago, I dropped my luggage in the hall and rushed to check on my octopus. He had been left in his tank for nearly a week without any company. To my surprise, he was nowhere to be seen. I was not really worried, since I could not see any sign of a body—a dead octopus is easy to find. I dropped a crab in his tank and expected to see him come out at any moment to consume his meal.

I checked several times during the next couple of days but never noticed the octopus. The crabs were gone, so I figured he was just avoiding me as punishment for abandoning him for the trade show. After about a week of not seeing him, I opened the canopy to clean the filter sponge and became concerned. There were all of the black crabs that I had tossed into the tank the previous week—they were all happily living in the filter chamber of the aquarium.

Goodbye, My Friend

I panicked. Where was my octopus? I again searched the kitchen to see if there was any evidence of a great escape. I couldn’t imagine he would have escaped a week ago and there would be no smell to detect his presence. But then I remembered that the housekeeper was present on the day I returned home from Chicago. Perhaps she had found his body and disposed of it, and I had been feeding crabs to an empty tank.

I was both mad and sad at the same time. I was mad at myself for not taking precautions I knew that I should have taken to prevent his escape from the tank. I was sad that I had allowed such a beautiful and rare creature to die. I decided right then that I would set up the perfect mimic octopus habitat and acquire another one. This time I would do it differently.

Starting Again

After a few days I decided to put some other fish into my tank so that guests at my upcoming Halloween party would not be asking “what’s in the tank?” I took home a couple of small marginalis butterflies, a couple of Buddha cardinals, and a small dragon wrasse. I acclimated each one and then let them out to venture into the aquarium. Just as I was closing the canopy I noticed a tentacle waving behind the rock. It was my mimic, alive and well! He waved his tentacle at me (or so I like to think) as I peered into the tank.

I immediately began to scoop the new fish out of the tank by hand. I managed to catch all but one of the butterflyfish, which hid behind the rocks. I left the other fish in the bucketful of transport water I had used to bring them home, deciding to bring them back to work the next day. But after some thought, I decided to put the Buddha cardinals back into the tank, figuring that if I could not catch the expensive butterflyfish, then I could at least give the octopus some other, less expensive targets for that night.


The next morning all the fish were still happily swimming around in the tank. Apparently, my octopus was not hungry for fish or crabs. I saw him sitting in the middle of the cave. He was not breathing abnormally, and his color looked fine. Then I saw what could explain the entire mystery of the untouched crabs and fish—a large cluster of eggs. He was a she! My octopus was guarding a clump of eggs about the size of my thumb.

Missing Information

Now I knew the end was near for my mimic. I have had experience in the past with Atlantic octopuses, and they lay eggs, quit eating, and die about the same time the eggs hatch. The babies will usually live a few days and then start to disappear. I tried researching mimic octopus reproduction on the Internet. I hoped that maybe they were different—after all, they are a diurnal animal, unlike the nocturnal Atlantic octopus. I hoped that maybe they had other differences also. Perhaps they could reproduce and still live. I could not find any information regarding reproduction habits. In fact, there is little information on mimic octopuses in general.


Then one night I walked into the kitchen and noticed a swarm of white octopuses in my aquarium. There were hundreds of them. They were mostly swarming near the surface of the water toward the light. There at the bottom of the tank lay their mother. She had died the same night they hatched. It is amazing how precise nature can sometimes be. The hatching took place at night, approximately four weeks after my return from Chicago.

The next morning, there were significantly fewer babies in the tank. I assume that some had died and that others may have found hiding places in the tank. Unlike the Atlantic octopus babies, who hatch looking like perfect miniatures of the parent, the baby mimics are much less developed. They almost appear like little jellyfish pulsing through the water. I wanted to hope, but I was not optimistic that any would survive for long. Whatever these little guys eat at this size, I was certain it was not swimming around in sufficient numbers in my aquarium.

The End?

I donated the remaining mimic babies to the Georgia Aquarium. They called a week later to tell me that, unfortunately, none of the babies survived the week. For all my years in the aquarium industry I had one chance to keep a rare octopus that many will never see in a lifetime. My hope is that if another mimic reproduces in captivity the owner will donate the babies to researchers who can better give them a chance for survival. Who knows what the future holds—perhaps tank-raised mimics?

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