Rhincodon typus – The world’s largest aquarium fish

Three holy grails of diving in a row: First the Mola mola, then the Manta, and now the Whale shark, picmybug is reaching for the stars (of diving)! And I was lucky enough to meet a Whale shark in the water recently!

I can repeat it, much is unknown about the most famous marine animals. It is true for Whale sharks as well.

The world’s largest fish is a beautiful creature which most, if not all divers, snorkelers and marine enthusiasts long to see in real. We’re talking about a harmless shark that can reach up to 18m, maybe more. Hundreds of white dots on a bluish-grey background on the entire top of the body look like a sky full of stars. Other sharks, whales and perhaps most other large mammals look dull compared to R. typus. It is an unforgettable moment to see one in the water, it made me feel tiny, and it had some magic. It’s like a mystical creature from a movie. How often do you see an animal more than twice your size!?

While most people, who have a minimum of a relationship to nature, know about the existence of Whale sharks, even dedicated divers hardly know more than the basics of their biology. They are huge and harmless, they prefer warm water (good for divers!), and they filter the ocean to feed on krill and plankton. And maybe fish? Where do they mate? How? How many eggs do they lay, or don’t they? In which depth do they spend the majority of their time? Are we looking at a male or female? That’s already a bit further in the dark.

So let’s collect some facts about Rhincodon typus before we come to story of Whale sharks in aquariums.

Sharks and rays belong to the subclass Elasmobranchii. Whale sharks share the order Orectolobiformes (carpet sharks) with e.g nurse sharks and wobbegongs. That’s surprising, since they never lay in the sand like their closest relatives. Probably? Within that order, R. typus is the only species in the family Rhincodontidae. Read more about the description further down in this blog!

The largest fish in the world grows to an unbelievable size of 18m, or even more, with females growing taller than males, but males growing faster. A very high number of encounters are with males, some surveys resulted in more than 75% males. I guess the whale shark in my picture is a male too, but I haven’t seen it from below. It was between 4 to 5m, estimated by our group divers.

It is not much known about their reproduction, but a female with around 300 pups was “found”. That’s what you read in different sources. More details were hard to get. “The whale shark, Rhincodon typus, is a livebearer: 300 embryos found in one ‘megamamma’ supreme” was published by Joung et al. from Taiwan in July 1996. I couldn’t find a free copy of it, but I assume neither the Megamamma nor the 300 babies survived this event. There is a market for Whale shark products in Asia, of course. I don’t know how and why they caught the Mama, and what happened to the bodies afterwards. There ratio of males and females is said to be 50/50, and the have been of different size, and have all the same father. Could it even be that the high number of embryos was abnormal and the cause of death? The podcast Hugabug 8 by lizwason says the Mama war harpooned by fishermen.

R. typus was described in 1828 by Sir Andrew Smith, a British who studied animals mostly in South Africa. We talked about common name confusion some month ago. Whale shark is Whale shark, pretty simple, but we had some scientific name confusion going on this time. Rhincodon translates as something like rasp tooth. They have thousands of tiny teeth, with unknown purpose. Rhincodon filter the water to feed on plankton and small fish. Could it be that they need teeth for mating, like the Mantas, whose males grab females by the fin? Or are they part of the filtration mechanism? We don’t know yet.

Let’s go back to the name.

Sir Smith described and named a huge fish caught in South Africa in April 1828 Rhiniodon typus. Seems he wrote Rhineodon by hand, but the typesetter misinterpreted the e for an i. In 1829 Smith published more works, and called the same fish now Rhincodon. Maybe he misinterpreted his e for a c this time?

I find it remarkable that the name has no relation to the stunning size or appearance of the shark. As if he wasn’t too impressed. The teeth aren’t the most obvious detail, are they? Over the years many spelling-versions of the genus existed, so that the International Commission on Zoological Nomenclature (ICZN) had to discuss and decide on “Opinion 1278” what name to finally use. It is their task to ensure that each animal goes by one name only. With fourteen to six votes Rhincodon won over Rhiniodon, and since 1984 this is the spelling of the genus for the Whale shark. This scientific name-confusion went on for 154 years!

The fish he described was caught in Table Bay, Cape Town, South Africa. It was fifteen foot long, 4.57 meter. He’s purchased the skin for six pound sterling, he noted. That equals 725 pounds nowadays. There isn’t much more information in the original description. Much more is written about the sea devil of Jamaica, which seems to be Mobula mobular. Read it here! Skip the part about the process of catching the ray, when you’re not up for some cruelty.

My story related to the largest fish in the world is about megalomania.

Do you support zoos? Do we have the right to capture animals for our entertainment, and commercial benefits? Does the display of animals help to create awareness about our environmental issues? That’s for sure complex topic. Less complicated to me is the question about the wellbeing of animals in captivity. I do have some experience in keeping exotic pets at home. I stopped it for various reasons, and I learned a few lessons from that hobby. One important thing is that you can keep some species successfully with very little effort. You can for example breed Mealworms easily. Many tarantulas will do well at room temperature. Freshwater fish like Mollies and Platys will easily sparkle joy in your living room. Such pets can be reproduced in captivity. Other species of exotic pets have to be imported in large numbers because they are popular and sought after, but won’t do well, and especially not reproduce. People wouldn’t learn from negative experiences, and keep buying more and more wildcaught pets. I really struggle to find justification for those procedures. We can’t simulate each and every habitat, and how could we without even knowing what the species needs?!

Believe it or not, the glorious Whale shark belongs to the category of unsuccessfully kept aquarium fish. The largest fish in the world, known to dive more than a thousand meters deep, hiding so many details about it’s biology yet, has been put in aquariums, mostly in Asia, with very little success. There are some websites that collect/ed data, which allowed me to gather this most recent information. I started with Elasmollet.org, a-z-animals.com, shorttraveltips.com, and searched for hints on details on YouTube, TripAdvisor, Google, social media and the aquarium’s websites.

Let me try to summarise how many Whale sharks died in aquariums, and how many are kept in the year 2022.

We’ll start with the only western aquarium that keeps Whale sharks. The Georgia aquarium imported two young males from Taiwan in 2005. Ralph survived for 18 month, Norton for 24 months. Both were meanwhile accompanied by also Taiwanese females, Alice and Trixie. Just a few days before Norton died, Yuchan and Taroko, from Taiwan, joined the group, so that for a few days five Rhincodon typus were kept. Read here how they transported the sharks. Good news: Catching and trading of Whale sharks in Taiwan is prohibited since 2008.

How are the remaining four doing more than 15 years later? Trixie died in 2020, Alice one year later. For a fish that might live more than a hundred years, I want to say they lived way to short! They did not reproduce, and from what I understand two males are left now. Narcity.com says there’d be four as of May 2022. But the aquarium posted on 31st August 2022 on Instagram that they’re proud of their two individuals. So only Yushan and Taroko are alive. Non-members can snorkel with them for 250 USD, or scuba dive with them for 350 USD. We note for Georgia: 4 died, 2 alive.

No surprise, the aquariums website doesn’t provide much information aside from the basic facts. The fact that they didn’t highlight Whale sharks in this article about the species of sharks they are keeping makes me believe that they might lost some enthusiasm. Just to be clear, I have no doubt that the experts there give their very best for the wellbeing of those Whale sharks. They rescued them from fishermen, who otherwise would have killed them immediately. And it would have been a great success to breed them in captivity.

All other aquariums with Whale sharks are located in Asia.

The National Museum of Marine Biology and Aquarium of Taiwan kept one male from 2005 till 2013. It grew from 2.3 to 7.8m, and was then released. It stranded immediately, and seemed to keep swimming in circles, like it does in its aquarium. Ellas Mollet reported in 2012 that they kept two unsuccessfully, then three at a time, and released one more. Overall I must say it is almost impossible to track the Whale sharks. I would say two dead, 2 released, 2 unknown.

The Yantai aquarium in North-east China gained a lot of attention by displaying five Rhincodon together. The aquarium is ten times smaller than the one in Georgia. There’s a video on YouTube, mentioning three individuals in the description. A photo from 2017 shows two Whale sharks with a wedding ongoing in their aquarium. I can’t find evidence other than this, so I figure there’s probably two left only. Let me know if you know more please! Otherwise I’d say Yantai: 3 dead, two alive.

Japan, Okinawa, Churaumi Aquarium: In 2019 they celebrated the world record, Jinta lives in their aquarium for 24 years. He is said to be mature since 2012. He was 8.5m long and approximately 25 years old. With that male lives one female. Ten years after his maturation no success of Churaumis breeding project has been reported unfortunately.

Mollet wrote in 2012 that they (under the name Okinawa Ocean Expo Aquarium) had sixteen between 1980 and 1998, and three in 2012. Wtf happened to them? Another source says three in 2015. Three out of at least 16 are traceable in 2022. They also have the so called Kuroshio Sea tank, where one female was transferred to for health reasons, sadly it died there in 2021. Assuming that Whale sharks can live for over a hundred years, the sixteen should still be alive in 2022, so I wanna count 2 alive, 14 dead. Or released? Unknown.

Also Japan September 2022: The Notojima Aquarium in Ishikawa released one of their Rhincodon into the ocean. Confusing: Another website says all two were released, and two smaller ones added instead. According to Wikipedia, Notojima kept Whale sharks since 2010. I cannot reconstruct whether the two specimen were the only ones before the current replacement. Mollet says no successful attempts until 2000, what makes me worried about unsuccessful attempts.

Kagoshima Aquarium in Japan keeps one Whale shark currently. They’re also claiming to release them after they’ve grown to big. Mollet reported a second one in 2012. On Zoochat.com user “Bagger” wrote down dates for the release of 9 Whale sharks between 2000 and 2018. If that’s true, and they release them after they grew to a certain size, fine. I’ll note 9 released, 1 kept in 2022. Not sure about last 4 years. I haven’t found any other source for the release events though.

There is a thread on Zoochat.com listing 8 for Chimelong Ocean Kingdom near Hong-Kong. This adventure park holds a few records including largest aquarium, and faces some criticism regarding their purchases of rare animals. There’s an article about diving with Whale sharks, with a maximum group size of 20 divers. I can’t find any current numbers, videos are showing maximum three at a time. So I’ll say 8 alive, with huge question mark.

I’ll leave it here, knowing that there will be more cases around. But reliable information are probably to be found in Chinese and Japanese language.

My summary is 47 Whale sharks were kept in aquariums since the 80s. 19 are alive and on display. 13 were released after a while, with unknown outcome. The fate of 16 Whale sharks is unknown to me. 8 are confirmed to have died in aquariums.

For clarification, and as a reference, Taiwan alone caught hundreds of Whale sharks annually before 2008. The Galapagos Whale shark project estimates a number of 6 to 8000 caught, killed and consumed Whale sharks each year.

So I’m not saying those attempts are putting the entire species at risk. Fishery for sure is multiple times worse. But trying to display the largest fish of the world in aquariums seems unnecessary to me.