9 min read People Are Killing Millions Of Fish Each Year Just To Stock Aquariums "It's a revolving door of cruelty and destruction."

<p><em>Teri Leicher</em><span></span></p>

In 2010, people in the Hawaiian city of Kona discovered something unexpected inside a dumpster - a plastic bag full of dead tropical fish. Most of the fish were yellow tangs, but there were also butterflyfish and surgeonfish.

The plastic bag of dead fish found in Kona. | Teri Leicher

They laid out the fish on the ground and counted - there were 610 of them.

610 dead tropical fish found in Kona. | Teri Leicher

To some people, a dumpster full of dead fish might not seem like a big deal. Yet Rene Umberger, founder of For The Fishes, an organization that advocates for the protection of wild fish, told The Dodo that the situation was incredibly alarming to her.

Teri Leicher

These fish had been caught off the coast of Hawaii, and they were going to be distributed to pet stores and aquarium traders across the U.S., Umberger explained. From there, the fish would be sold to people who wanted tropical fish in their aquariums.

Teri Leicher

Yet something had gone horribly wrong, and these 610 fish had died before they were shipped away.

Teri Leicher

"It was likely a mechanical failure [in their holding tanks] that deprived them of oxygen and allowed buildup of deadly waste," Umberger told The Dodo. "People who capture and trade in this wildlife for a living care very little about the well-being of these animals. The goal is to sell these animals before they die and pass the risk onto the buyer. It really is quite ugly."

Teri Leicher

It's estimated that around 20 to 24 million tropical fish are taken from the oceans each year to be sold in the aquarium trade, according to a report published by the United Nations Environment Programme (UNEP). The Philippines and Indonesia are the biggest exporters of tropical fish for aquariums, and there's also a huge aquarium trade in Hawaii.

For The Fishes

But there's a huge mortality rate as well - fish often die during the capture and transport processes, Teresa M. Telecky, senior director of the wildlife department for Humane Society International (HSI), told The Dodo, making the whole process incredibly cruel. "Many fish are captured at depths that, when they are quickly brought to the surface, causes barotrauma, just like scuba divers would experience if they surfaced too rapidly from deep water," Telecky said. "Barotrauma causes physical damage to body tissues which can overstretch or rupture. Fish brought up too quickly will have bulging eyes and cloaca." Fish collectors will also pierce a fish's swim bladder to quicken the capture process, Telecky explained.

Divers using nets to catch fish in Hawaii. | Paul Cox

"Aquarium fish collectors are in a rush to get their fish to market, so instead of taking the time to decompress the fish by slowly bringing them to the surface, they instead skewer the fish with a needle aimed at the fish's swim bladder, a technique called 'fizzing,'" Telecky said. "This causes physical damage to the fish's scales, skin, circulatory system, muscle and the swim bladder, which is an organ."

Divers using nets to catch fish in Hawaii. | Paul Cox

In Hawaii, fish tend to be collected with nets. But in the Philippines and Indonesia, fish collectors use a highly toxic compound called cyanide, which stuns fish and makes them easier to catch.

A diver using cyanide to collect fish. | James Cervino/NOAA

"They crush up these [cyanide] tablets inside these squirt bottles," Umberger said. "Then they mix it with salt water and they squirt it out. Fish that are closest to that are going to die almost immediately. You can see them gasping for air."

"When cyanide is squirted onto a reef, 50 percent of the reef and animals who are exposed, die," Umberger added. "Within hours, another percentage dies. Within days, another. It's destroying reefs and entire ecosystems." If fish don't die from the cyanide, they often die while being transported.

"Fish are transported to market in small plastic bags that contain very little water that becomes contaminated with fish excrement during the long transport process, which can be several days," Telecky said. "To avoid too much fish excrement in the water, traders often starve the fish for 24 or 48 hours before shipment, which is very unnatural, especially for fish who graze all day. Fish dorsal spines, which are part of the animal's skeleton covered by skin, are often cut off so that the plastic bag is not punctured."

A yellow tang being transported in a plastic bag. | Robert Wintner/Snorkel Bob

If the fish do happen to make it to their destination, they often don't live long in aquariums anyway, according to Telecky.

A dying yellow tang lying on the bottom of an aquarium. | For The Fishes

"Most wild-caught marine fish do not survive long in captivity, particularly in average home aquariums, which keeps the demand for new 'replacement' aquarium animals high, meaning more damage to wildlife populations," Telecky said. "It's a revolving door of cruelty and destruction." "For every fish sold, 6 others died from reef to retail," Umberger said. She also estimates that tens of millions of fish die each year in the global aquarium industry. One of the most surprising things about the industry, Umberger said, is how few people know about what's going on, and that 98 percent of tropical fish in aquariums are caught from the wild. "What we've learned is that people just don't know that these animals are captured to begin with," Umberger said.

A dying yellow tang lying on the bottom of an aquarium. | For The Fishes