Thailand is to suspend the exporting of seahorses, traded by the millions annually as an ingredient in traditional medicine in parts of Asia.
A marine biologist who works closely with Thailand on seahorse conservation welcomed the government's decision to suspend seahorse trade because of concern about threats to its wild population.
"It's a way station to getting serious management in place," Amanda Vincent of The University of British Columbia said.
Ms Vincent is director of Project Seahorse, a marine conservation group whose partner is the Zoological Society of London.
The Thailand decision was announced at a meeting in South Africa of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or Cites.
The UN meeting, which regulates trade in more than 35,000 species of animals and plants, ends on October 5.
Seahorses are mainly used in dried form for traditional medicine in mainland China, Hong Kong and Taiwan.
They are also popular as curios, and there is a trade in live seahorses for display in home aquariums, including in Europe and North America.
Cites requires some controls on trade in the dozens of types of seahorse, designed to ensure the survival of the species.
But Thailand, responsible for three-quarters of the world's documented exports of seahorses, could not meet its obligations and stopped issuing export permits at the beginning of the year, according to Ms Vincent.
Thailand's goal, she said, is to make seahorse exports "sustainable."
Cites has suspended the seahorse trade with three other big exporters - Vietnam, Senegal and Guinea - after they failed to meet requirements for the trade in the animal, Ms Vincent said.