Domesticating Nemo

Saltwater aquariums are undeniably beautiful. Glass tanks filled with darting jewel-bright fish, swaying corals and scuttling invertebrates have been mesmerising humankind since the 1960s, and the aquarium hobby has only grown in popularity in the half-century since. While advances in technology have revolutionised the designs and capabilities of saltwater systems over the past few decades, until recently, the creatures kept in them have remained largely identical to their wild counterparts.

Clownfish have long been among the most popular and identifiable of saltwater aquarium residents—never more so than after the release of Disney Pixar’s 2003 smash hit Finding Nemo, which put the collection of reef fish on the global stage. In recent years however, these colourful ambassadors of the oceans have started to look, well—a bit different.

The New Face of a Familiar Fish

Photo by Brian Williams / Clownfish Depot
Photo by Brian Williams / Clownfish Depot

Once confined to a consistent configuration of oranges, reds and browns (with a few exceptions) interspersed with smart white stripes, modern clownfish are now available in an incredible range of hues and patterns. These changes are the result of domestication—involving selective breeding of individuals with certain desirable traits, as well as directed hybridisation between different species.

Of the 30 species of clownfish currently known to science, roughly 13 are regularly available for purchase in the aquarium trade. Of these, about 11 species are consistently farmed in captivity by large companies, which sell fish at wholesale prices to local aquarium shops and online retailers.

During the past decade, designer clownfish varieties with catchy names like Picasso, Snowflake, Dalmatian, Da Vinci, Black Ice, Platinum and Naked have emerged on the market, providing consumers with a huge number of additional options for populating their private slices of the sea. Unlike wild clownfish, which typically have full white bars and symmetrical patterns, designer clownfish are prized for traits such as asymmetrical ‘misbars’, spots, and large white patches that often appear like pieces of a jigsaw puzzle.

Due to both the novelty and the limited availability of individual ‘breeds’, designer clownfish typically fetch much higher prices than either their ocean-caught or captive-bred ‘wild type’ relatives. With the financial incentives and countless possible outcomes of genetic intermixing, this practice will undoubtedly continue, producing unimaginable new forms of this iconic fish.

A Piece of the Sea


The farming of aquarium fish, invertebrates and corals, a process known as ‘aquaculture’, is undeniably a net positive for the environment. Farm-raised animals directly replace those that would otherwise be harvested from the wild, often through unsustainable fishing practices. Additionally, aquacultured fish tend to live healthier lives in captivity, as the animals are already accustomed to aquarium life and commercially prepared diets, reducing the need for frequent replacements of tank residents.

Prior to the turn of the 21st century, the saltwater aquarium industry relied almost exclusively upon wild-caught animals. Even today, the vast majority of livestock involved in the global marine aquarium industry, which has an estimated value greater than £4.9 billion annually, is collected from the wild.

In some parts of the world, fishing techniques that use dynamite or sprays of cyanide to stun marine animals are commonplace—practices that often do widespread damage to the surrounding reefs and cause heavy die-offs among collected fish and invertebrates. Even when techniques are ideal, wild collection of marine animals can create issues through overfishing, by removing species that have key roles in the maintenance of reef ecosystems.

This is not to say that wild collection of marine ornamental species is exclusively harmful to the environment. Sustainable collection of reef organisms can provide a valuable source of income for local communities throughout coastal areas of the tropics, which are often economically depressed. This durable source of income can encourage local fishermen to become stewards of the reef, and to manage marine fisheries as a vital component of their livelihoods.

Nonetheless, the lack of transparency and oversight involved in the collection of marine species, combined with fierce competition, often translates into less than ideal impacts on marine ecosystems. Aquaculture has the potential to mitigate the damage to reef habitats and reduce pressure on heavily traded species, which are increasingly threatened by environmental factors like climate change and ocean acidification.

Farm to Tank

Photo by Brian Williams / Clownfish Depot
Photo by Brian Williams / Clownfish Depot

Aquaculture of ornamental species is hardly new. In fact, the farming of ornamental freshwater fish dates back to the 1920s. Current estimates place the percentage of captive-bred freshwater aquarium fish at around 90%, with only 10% still collected from the wild. Contrast this with the saltwater aquarium industry, in which roughly 5% of ornamental species are produced through aquaculture, and the growth potential of marine aquaculture becomes clear.

As the industry matures, the farming of saltwater aquarium species is likely to follow a similar course to the one blazed by the freshwater aquaculture industry throughout the twentieth century. In many ways, the advent of designer clownfish is evidence of this trend. So-called ‘fancy’ varieties of many freshwater species have been available to consumers for decades, maintained in well-known breeds that bear little resemblance to their ancestors in the wild.

The production of traits such as long flowing fins and dramatic patterns typically involves processes like inbreeding and genetic bottlenecking, which can reduce the health and overall fitness of ‘fancy’ fish. This isn’t really a problem in captivity, however, as the safety and stability of aquarium life eliminates the harsh pressures of natural selection that weed out the very traits that are prized among ornamental animals.

Some Cause for Caution

Unfortunately, domesticated species can and do sometimes escape into the wild.

In recent years, conservation headlines in the Americas have been consumed by a very real example of an aquarium fish interacting with wild ecosystems.

Lionfish, which are native to the reefs and waters of the Indo-Pacific, have now become established throughout the warm waters of the Western Atlantic Ocean. Scientists from the US National Oceanic and Atmospheric Administration (NOAA) believe these invasive populations were likely started by well-intentioned aquarium owners, who—for whatever reason, chose to release their pets into the wild.

Lionfish are popular with aquarium keepers, largely owing to their showy venomous spines and dramatic warning coloration of alternating red and white stripes. Due to their robust natural defences, lionfish have almost no predators outside of their native range, allowing populations of these efficient predators to grow largely unchecked since the 1990s.


Photo by Florida Fish and Wildlife / Flickr
Photo by Florida Fish and Wildlife / Flickr

Coupled with a rapid rate of reproduction, these traits have made lionfish a devastating invader to reef ecosystems throughout the Atlantic. Despite organized control efforts, lionfish populations are predicted to continue to expand in future years.

Unlike lionfish, which some scientists have called ‘mouths with fins’, escaped clownfish pose no discernable risk to marine ecosystems. Their small size and poor swimming abilities make them easy targets for predators, particularly when separated from the host anemone species that act as their natural symbionts.

Still, as the lionfish example shows, aquarium fish can have significant interactions with wild ecosystems. While heavily domesticated species are likely to be quickly eliminated through natural selection, escaped hybrids have the potential to cause larger impacts.

Evidence of a Trend


Photo by Lisa Charbonneau / Shutterstock
Photo by Lisa Charbonneau / Shutterstock

The domestication of clownfish is the first step in a process that will likely keep pace with the growth of marine ornamental aquaculture. Of the roughly 35 saltwater species that have been successfully bred in captivity so far, only a few have been included in serious selective-breeding and domestication efforts.

This situation is likely to change, however, as improvements in techniques and technologies allow the aquaculture industry to extend its reach to include new marine species. As human creativity and genetics intersect, only one thing is for certain—consumers can expect to see new and fantastic forms of marine life entering the market in years to come.