Do You Know Where Aquarium Fish Come From? The Answer Might Shock You

Pet fish lovers beware, your aquarium might contain a dirty little secret. New research shows that the overwhelming majority of aquarium fish sold in the U.S. are caught from the wild.

Scientists studied several large online aquarium retailers based in the U.S., finding that of the hundreds of different fish species sold at these places, about 90% were collected from the wild. Dozens of species sold by these retailers were also found to be facing population threats, indicating that the aquarium trade is actively harming marine conservation efforts.

Wild and not free

The study’s lead author, Bing Lin, conducted this research as part of his doctorate at Princeton University.

“As my PhD supervisor and study co-author, Professor David Wilcove, would say, this study sat at the perfect intersection of interest, importance, and feasibility,” Lin told Gizmodo. He is now a postdoctoral research associate at the University of Sydney’s Thriving Oceans Research Hub.

“Earlier parts of my PhD focused on web scraping, the wildlife trade, and marine conservation. This project brought those threads together into a single, data-driven look at a massive but understudied global trade,” Lin said.

All in all, Lin and his team analyzed data from four major U.S.-based aquarium retailers. They identified 734 different species across 13 broad families of fish being sold at these stores.

Almost all of these species—665—were sourced exclusively from the wild, they found, while only 21 species were sourced entirely from marine farms, also known as aquaculture. What’s more, 45 of the species they identified are known to be experiencing population declines, with 20 of these classified as threatened. Of these at risk fish species, 38 were sourced completely from the wild.

The team’s findings, published Wednesday in Conservation Biology, likely underestimate the problem, Lin said. Their data only included fish families known to have at least one species commonly bred in captivity, meaning the true proportion of wild-caught fish may be higher. They also didn’t investigate other commonly sold sea life for aquariums, including invertebrates like corals and crustaceans.

A place for aquarium fish

Aquariums don’t have to be part of the problem. In fact, ethically-sourced, ornamental fish could be good for everyone.

Lin and his team found that fish bred in aquaculture tended to be cheaper than those caught in the wild—on average 28.1 percent less expensive for the same species. There are also communities in parts of the world like the Indo-Pacific that have started to rely on sustainable fisheries as an important part of their economy.

Strategies like supporting these fisheries, creating new regulations governing the sale of fish for aquariums, and tempering the demand for threatened species can all help keep the oceans safer, the authors argued. Lin and his colleagues at the Thriving Oceans Research Hub plan to continue investigating the aquarium trade, with a special focus on the world’s “bright spots,” where sustainable fishing is already happening.

Still, Lin cautioned that more data is needed to better understand the scale of the problem. For example, the researchers identified about 100 species of fish being sold by retailers that aren’t currently listed as common aquarium species by major fish or conservation databases.

“We can’t improve what we can’t measure,” Lin said. “Better traceability and oversight are critical—right now, the trade’s supply chains are largely opaque, which means that we often don’t even know what we don’t even know.”