Market for Nemo

Coral reef fish imported to the United States for saltwater aquariums are more diverse yet less numerous than previously thought, a new study suggests.

The study, published in the journal PLOS One, found that fishes comprising 1,802 species from 125 families were imported into the United States over a yearlong study period. Previous estimates of diversity based on government import forms were 22 percent lower.

Yet only about 11 million individual marine fish were imported, not the 15 million indicated on declaration forms.

It’s the “onesies and twosies,” the species found in only a few tanks, that are most interesting, Andrew Rhyne, the lead researcher and a marine biologist at Roger Williams University and the New England Aquarium, remarked in a telephone interview.

Nonetheless, 52 percent of the fish imported during the study period were from only 20 species, the study found. And damsels and anemone fishes from the Pomacentridae family made up half of the top 20 species and about three-quarters of the individuals.

The international trade in colorful marine organisms from coral reefs has become big business over the past 15 years. New lighting and filtration technology enabled hobbyists to set up saltwater aquariums at home, and the popular 2003 movie “Finding Nemo” buoyed demand for clownfish. According to the federal Fish and Wildlife Service, one million of the world’s 1.5 million aquarium hobbyists live in the United States, and Americans buy more than half of all marine aquarium fish sold globally.

Until now, little has been known about these imports. To gather hard data, Dr. Rhyne recruited a team of students to examine more than 8,000 shipment declarations and corresponding invoices provided by the National Oceanic and Atmospheric Administration and the Fish and Wildlife Service dating from May 2004 to May 2005.