Watching flamboyantly colored fish flit about a saltwater aquarium can be relaxing. Figuring out where they came from, and whether they were caught in a sustainable manner, can be an exercise in frustration.

The aquarium trade is a global industry with no centralized database to track what gets bought and sold, and with no central governing body to enforce regulations. Collectors and exporters in places as far-flung as the Philippines, Sri Lanka, and Florida pump tens of millions of marine animals—more than half of which end up in the U.S.—into the multimillion-dollar business each year, often with little or no oversight.

About 1,800 tropical fish species are involved in the international trade, says Andrew Rhyne of the New England Aquarium in Boston and Roger Williams University in Bristol, Rhode Island. Hundreds more species of invertebrates, including live corals, are also part of this pipeline.

Removing animals from the wild can have serious consequences-both for their survival as a species and for their habitat. But the effects vary from species to species. Green chromide fish, for instance, are quite plentiful in the wild, says Rhyne, and their "population is under no threat at all from [aquarium] collection." On the other hand, species like the royal or regal blue tang—the fish that Dory from Disney/Pixar's Finding Nemo was based on—have been overcollected and are in danger in the wild.

Now a campaign to stop the collection of reef fish in Hawaii, spearheaded by the group Sea Shepherd, is bringing some of these issues to light.

The organization is hoping its Reef Defense campaign will help push through stricter state laws and regulations in Hawaii dictating the collection of reef organisms for the aquarium trade, says Michael Long, director of the campaign. Eventually, he says, "we hope that the aquarium trade will be banned altogether."

View Images A man holds up a Banggai cardinal fish (left) and a clownfish (right) caught in Indonesia for the aquarium trade. Photograph by © Nicolas Cegalerba, Biosphoto/Corbis

Catch as Catch Can

Of course, the very laws (or lack thereof) that govern the aquarium trade are part of the problem. Regulations and enforcement vary as widely as the geographic locales where fish are collected, says Rhyne.

"Some fisheries are really well managed," he says, "like Hawaii." Australia and Fiji also manage their aquarium trade activities fairly well. But the Philippines and Indonesia—which together account for about 86 percent of the fish imported into the U.S.—have some of the more poorly managed fisheries.

For instance, it's illegal to use cyanide—a poison that can stun fish and make them easier to catch—in the Philippines, says Brian Tissot, director of the marine laboratory at Humboldt State University in Arcata, California. "But almost half the fish coming out of the Philippines [are] treated with cyanide."

Enforcement in the Philippines is left up to local municipalities, which usually lack the resources to police their waters.

Coming to America

On the demand side, tracking animals imported into the U.S. for the aquarium trade is a daunting task.

It's mandatory to monitor imported species listed by the Convention on International Trade in Endangered Species (CITES), and there are databases dedicated to those species. But the only animals on that list that are also involved in the aquarium trade are stony corals, giant clams, and seahorses. According to a 2012 study on the U.S. marine aquarium trade, the majority of fish are lumped into a single category—marine tropical fish (MATF)—by the U.S. Fish and Wildlife Service.

If researchers want to look at the species and volume of fish coming into the U.S., they have to drill down into specific shipping invoices. For their 2012 study, Rhyne and his colleagues needed three years to sift through shipping data from 2005 alone. (The researchers are close to publishing their findings for subsequent years.)

Florida supplies more invertebrates (except for corals) to the industry than anyplace else does. And officials there do a fairly good job of tracking what fishermen bring in, says Rhyne. But they lack life-history data on many of the animals—including how fast they grow, how often they reproduce, and what their development from larvae to adult looks like.

"If you're fishing something intensively," Rhyne says, "you really need that kind of data to manage it properly." Otherwise, "you run the risk of overfishing [a species] and not knowing it."

Raising Nemo

Having that bank of knowledge can be incredibly helpful in an industry that can change quickly.

The 2003 movie Finding Nemo caused a "30 to 40 percent surge in demand for Nemo [a clownfish] overnight," says Rhyne. Fortunately, he says, clownfish were already being cultured in captivity, so there were enough to satisfy the increased interest. "Otherwise, that demand would have been taken out of the wild population." (Read about clownfish and their host anemones in National Geographic magazine.)

But the regal blue tang hasn't been so lucky. This species is hard to raise in captivity, Rhyne says, so "it's been overcollected in Indonesia and the Philippines."

These fish feed on algae, an organism that could overgrow the coral if the fish didn't keep it clear. Removing regal blue tangs from a reef could leave corals in jeopardy of being smothered.

So what should people do if they're thinking about starting an aquarium? The most important thing, says Rhyne, is for them to educate themselves. Taking the time to find captive-bred animals, like clownfish, is a good way to start.

"If they're not willing to educate themselves, they shouldn't have an aquarium," Rhyne says. Because "the things we buy over here have a big impact on coral reefs."