The Dory Effect

Will Finding Dory result in a surge in blue tang purchases in the hobby?

Blue Tang (Paracanthus hepatus). Via Rain0975/Flickr

The amazingly popular Pixar movie “Finding Nemo” was released in 2003 and immediately triggered a rise in the popularity of clownfish in the marine aquarium trade. Anemonefish have always been a staple in the hobby as they are one of the more robust species that is both long lived and has moderate space requirements, but this animated film certainly boosted demand for these animals. Orders for A. ocellaris at ORA (Oceans, Reefs and Aquariums) went up by 20 percent shortly after the movie came out and many retail stores reported a surge of first time customers coming in looking to “buy a Nemo.”

Ocellaris clownfish became extremely popular with the release of Finding Nemo, but for the wrong reasons. Photo by Alex Rose

Many articles surrounding this topic suggest that there has been a strong correlation between the decline in wild clownfish populations in association with the movie, but after reading the actual studies it was unclear if the effects of climate change, coral bleaching, El Niño years, human coastal development, and food fisheries could be tweezed out enough to come to this conclusion. One study compared clownfish populations on the same reefs in Australia in years before and after the release of “Finding Nemo” and it concluded that there had been an approximate 25 percent decrease in the clownfish populations studied. Coral bleaching has a measurable negative impact on the health of anemones and consequently clownfish populations, and since bleaching events had occurred on the reefs studied it was unclear what role collection played in the clownfish decline. No matter the exact correlation, it is safe to assume that reefs stressed by environmental factors are more susceptible to degradation as a result of unsustainable overharvesting.

Will the release of “Finding Dory” spur a rash of blue tang purchases?

A follow up study hasn’t been done to reassess the current status of these same populations, but after more than a decade and an explosion of captive bred clownfish, it is likely that the collecting pressure for this species has been drastically reduced. In the early 2000s it was estimated that about half the clownfish sold were wild caught, but this is certainly not the case any longer. It is far more common now to see captive bred clownfish in stores as opposed to wild caught specimens, and the low prices tend to indicate that there is no supply shortage. Clownfish have been successfully bred commercially since the 1970s when Martin Moe first officially documented his experience breeding and rearing A. ocellaris. His detailed account of the process allowed many hobbyists at a variety of experience levels to breed clowns in captivity, and today almost every species of clownfish has spawned in a captive environment. In recent years, particularly since the establishment of MBI (Marine Breeding Initiative) in 2009, efforts to drastically expand the list of commercially available captive bred marine ornamentals have increased annually. 271 species are currently on the MBI list, but most of these are not produced at a commercial level. That’s not to say they can’t be, but the current buying trends for most species still rely heavily on wild collection, though even this is changing. And this progressive push toward limiting wild collection in favor of captive breeding couldn’t come at a better time. “Finding Dory” is scheduled for release in June 2016.

Unlike clownfish which take well to the captive environment, are hardy, adaptable, and don’t require much living space because their homes ranges are tiny even in nature, many other marine fish species don’t quite fit this specific bill. Take for example “Dory”, the blue tang, Paracanthus hepatus. This fish really shouldn’t be housed in anything less than a 200 gallon tank, swims long distances, never seems to stop moving, and spends its day grazing on algae. P. hepatus can be maintained by a dedicated aquarist with the proper tank requirements, but this generally does not describe the beginner hobbyist looking to have Nemo and Dory for the kids. Aside from the less than standard setup needed to happily keep a blue tang, these fish have yet to be commercially bred in captivity, meaning that every individual has been collected from the wild. While there have been reports of captive bred blues out of Taiwan since 2011, the lack of photographic evidence and detailed documentation have drawn much skepticism, leaving many to question the extent of the truth behind this claim. The very recent success of Ocean Institute in Hawaii with breeding yellow tangs (Zebrasome flavescens) is extremely encouraging and promises a near future where we can hopefully expect tangs that were not wild collected, but until then, reefs will be the only suppliers of these fish to the hobby.

Chrysiptera parasema is a damselfish with similar coloration to the blue tang. Photo by Brian Ong/Wikipedia

If Pixar’s new ocean movie sees success anything like the first installment, then it is plausible to assume that demand for not just clownfish but also blue tangs will increase. With no captive bred options for this particular species, this surge in demand would certainly be to the detriment of wild populations. I am of the opinion that the sale of tangs of any variety to nascent hobbyists who are likely to want an aquarium for the questionable function of disposable living entertainment for their kids should be discouraged. Perhaps it would be reasonable to strongly suggest hardy alternatives to Blue tangs that have the same color scheme but that are smaller and more suited to aquarium life. For example, certain damselfish species such as Chrysiptera parasema, C. hemicyanea, and C. taupou have the same vibrant blue bodies and bright yellow tails and all three have been and can be bred in captivity. As damselfish are extremely abundant on reefs and reproduce quickly in the wild there has been little demand to produce these species in captivity in large quantities, but if they are marketed as an alternative to P. hepatus this could change.

Crysiptera hemicyanea is another damselfish that sports coloration similar to the blue tang of “Finding Nemo” fame. Photo by Haplochromis/Wikipedia

All three of these fish can be maintained in relatively small aquariums of 30 gallons or more and have healthy, omnivorous appetites that make a beginner aquarist’s chances of success much higher than with a tang. Offering damsels as a substitute for tangs when catering to an audience that wants “Nemo and Dory” diverts the pressure from vulnerable populations of wild tangs to fish that are far more abundant and could easily be captive bred. There is also the cost disparity between tangs and damsels to consider. On average, a blue tang sells for around $50 while all of the aforementioned damsels retail for less than $10. A cheaper fish is much more attractive to someone just getting into the hobby and this fact can be used as another point to dissuade the purchase of tangs by a certain demographic.

One foreseeable issue is that damsels are typically quite territorial and aggressive and a large damsel in a tank with a small clownfish would likely not bode well for the latter. An adult clownfish or pair of clownfish with a juvenile damsel would be a better bet for both species.

Damsels with coloration similar to that of blue tangs could be great alternatives for people looking to recreate these Pixar films in their home aquaria while avoiding negative environmental impacts and high mortality rates.

Alex Rose
Alex Rose holds a B.S. in biology and a M.S. in aquatic biology, and she has a wide variety of experience in the biological sciences, including bioacoustics research, exhibit construction, science writing, teaching, public presentation, and aquatic animal husbandry and breeding. Alex is a professional violinist, photographer, PADI divemaster and lover of all things aquatic. Her driving goal is to find ways to protect our world’s marine habits through diving, writing, education and research. Visit her website at You can also read more on the Sustainable Reefkeeping page

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Article Categories:
Fish · Saltwater Fish

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