This Destructive Practice May Be Responsible For Your Exotic Pet Fish


The colorful fish swimming around in saltwater aquariums around the country may look pretty, but the way they ended up in those aquariums is anything but.

A new report by the Haereticus Environmental Laboratory and nonprofit group For the Fishes tested fish from pet stores in five U.S. states. It found that over half of these fish tested positive for exposure to cyanide, a dangerous chemical that can kill the fish and destroy their reef habitats. Collecting fish from coral reefs using cyanide isn’t legal in the Philippines, Sri Lanka, and Indonesia — the countries where much of the world’s imported reef fish come from. But poor law enforcement means that fish collectors in these countries still often spray cyanide over reefs, stunning the bright reef fish they’re seeking to collect and bleaching or even killing the surrounding coral.

You just killed whole reef that was touched by this plume of cyanide.

“You’ll have divers go down there with little squirt bottles — and sometimes big squirt bottles … 20-gallon tanks — of Clorox bleach or cyanide and they’ll just blast whole reefs,” said Craig Downs, lead author of the report and executive director of Haereticus Environmental Laboratory. “It’ll kill a whole bunch of invertebrates like Christmas tree worms, shrimps, and lobsters.” And right now, when the world’ oceans are experiencing their third mass coral bleaching event in recorded history, extra stressors like cyanide pollution are “a death sentence” for corals.

“You just killed a whole reef that was touched by this plume of cyanide,” Downs said.

And the cyanide hurts the fish that are being collected, too. It’s a widely-known that pet store fish often die just days after being purchased, but when it comes to these reef fish, it’s often cyanide that causes early death; the chemical can prove deadly to fish within three weeks of exposure.


Downs’ report isn’t the first to examine this damaging practice that fuels much of the exotic fish trade. An analysis released Thursday by the Center for Biological Diversity and For the Fishes found that the United States imports 6 million tropical fish that have been exposed to cyanide each year. And previous research has also shown that 98 percent of saltwater fish species can’t be successfully bred in captivity — at least not well enough to support commercial demand for the fish. Breeding fish in captivity isn’t easy, Downs said: Many species have different food needs for different stages of development, and unless experts know exactly what these needs are, the fish won’t survive.

One of the fish species that isn’t yet able to be bred in captivity, or “cultured,” is the blue tang — a species that’s the star of Disney/Pixar’s Finding Dory, which is hitting theaters Friday. It’s a movie that’s worrisome to many marine experts, because it could lead to a surge in demand for blue tangs for home aquariums.

A blue tang, the starring species in Finding Dory. CREDIT: shutterstock
A blue tang, the starring species in Finding Dory. CREDIT: shutterstock

That’s happened before: Back in 2003, when Finding Nemo came out, sales of clownfish soared. Clownfish are one of those species that can be bred in captivity, but since experts haven’t figured out a way to culture blue tangs, any surge in demand will likely lead to an uptick in illegal collection of the blue, black, and yellow fish. That’s why many marine scientists are pleading with the public to avoid purchasing blue tangs, a fish that, as a coral grazer, plays a key role in the health of the coral reef ecosystem.

“I have only one thing to say to people who want to keep blue tangs … DONT!” Macquarie University behavioral ecologist Culum Brown told NPR. “There is every chance that your blue tang was illegally collected from the wild. There is no point in supporting that industry and killing the fish in the process.”

Disney, for its part, has put out an educational fact sheet on “selecting the right pet fish,” which notes that blue tangs, “like Dory, do not make good pets so instead choose appropriate aquacultured fish.”


A 2008 report from the National Oceanic and Atmospheric Administration estimated that up to 90 percent of the tropical fish that are exported to the United Sates each year are caught using cyanide. That’s a lot of fish — NOAA also estimated that a total of 11 million reef fish come into the United States each year. Corals, invertebrates, and other marine species are also targeted: A 2012 study found that “over 150 species of stony corals, hundreds of species of non-coral invertebrates, and at least 1,472 reef fish species from 50 families” are collected for use in the exotic fish trade.

That number points to just how big of an industry the exotic fish trade — which may seem like a niche hobby — has become. Recent statistics are hard to find, but a 2003 report from the United Nations Environment Program estimates that trading organisms — including reef fish and corals — for aquariums around the world is worth between $200 and $300 million each year. And while the practice has grown in popularity, buying and maintaining saltwater aquariums is still an elite hobby: Downs said saltwater fish purchased from pet stores can cost anywhere from $110 to $500, while some can be closer to $1,000.

Right now, U.S. agencies don’t regularly test imported fish for cyanide, even though importing the illegally-caught fish would be against the law. A legal petition filed in March wants to change that. In it, environmental and animal rights groups called on the U.S. Fish and Wildlife Service, NOAA, and U.S. Customs and Border Patrol to require “testing and certification to ensure imported tropical fish have not been illegally captured using cyanide” and to direct agency employees “to reject and seize live tropical marine fish imports that test positive for cyanide exposure.”

“In the U.S., there are currently few safeguards in place to ensure tropical marine fish in the aquarium trade have not been caught illegally using cyanide inviolation of federal law,” the letter states. “We strongly urge NMFS and USFWS to vigorously investigate and pursue aggressive enforcement action against any entity importing illegally-taken fish,” it continues.

For concerned consumers, there’s Tank Watch, an app from For the Fishes that provides data on which pet store fishes can be purchased without harming coral reefs. Downs is working on patenting technology he and other researchers have developed that would allow consumers to test their own fish for cyanide exposure. That technology would help agencies test for exposure too, he said. But until that happens, avoid buying blue tangs — and the other 98 percent of imported species that can’t be bred in captivity — if you want to keep coral reefs healthy.