Conservationists say that irresponsible collection methods - including cyanide fishing, tapping on habitats to scare fish into the open, and breaking off chunks of reef to remove key species - harm delicate environments already under pressure from such stresses as climate change.

Poor handling means that fish die in transit to the United States, Europe and other places where aquarium keeping is popular. But those that survive fetch high prices, so collectors catch as many as they can to allow for these losses, often resorting to environmentally unfriendly practices.

Farming fish could be a solution. Some popular species - including anemone clownfish and certain corals - breed successfully in tanks, but the spawning cycles of most are too vulnerable for success. And unless it is done in local communities, farming can deprive small-scale collectors of their livelihoods.

Supporters of the trade argue that, with education and training, communities, exporters, importers, retailers and hobbyists could both ensure a living for local people and promote the conservation of coral reefs. The Marine Aquarium Council (MAC) - which has developed sustainable trade standards - trains and certifies collectors, wholesalers and retailers. This gives collectors sustainable livelihoods and assures buyers that they are helping to conserve coral reefs.

Tank tips

• Look for the MAC certification label, but be aware that not all certified retailers only stock MAC fish.
• If you can't find MAC-certified marine ornamentals, buy those you know are likely to minimize impact.
• Tell people about your concerns. Write to specialist magazines and start discussions in online forums.
• For more information and a list of MAC-certified importers and retailers, visit www.aquariumcouncil.org.