Copyright_A_HoffordFishing with cyanide (hydrogen cyanide, HCN) has been illegal for a long time. However, using cyanide or quinaldine is common practice in South East Asia (Indonesia and the Philippines), where most of the coral fish come from.

Research shows that up to 80% of the targeted fish die: on-site, during transport or in the aquarium because the poison weakened them. The fishermen are also affected by the poison. The poison also ends up killing a lot of invertebrates and other fish who were not the main objective of fishermen.

This method involves dissolving cyanide tablets in plastic bottles filled with seawater. The fishermen then dive down to coral heads and spray the poison into coral crevices where the fish often hide. The poison stuns the fish, making them easier to catch. Coral branches are broken off to reach the hiding fish.

This method ensures a quick catch of many fish. It is cheap, efficient and therefore economically viable – so fishermen take the risk of being exposed to cyanide. Environmental protection laws are in place but are barely implemented and corruption is the order of the day.

Non-destructive fishing methods (e.g. hand-held nets) can also be detrimental to the reefs depending on the size and the distribution of the species (see fishes).

Fish which are collected from greater depths should be placed in cages and brought to the surface very slowly (3 m every 30 min.) to keep the swim bladder intact. To save time, fish are often taken to the surface swiftly and the inflated swim bladder is punctured with a needle passing through the abdomen. Watch film.

Stony corals lose their zooxanthellae (a symbiotic relationship with these green algae means that they cannot survive without them) when they come in contact with cyanide – they become bleached. A short time later, the animal colony drifts away from the calcareous skeleton and dies.

Stony corals for aquariums are even more difficult to breed than coral fish. Less than 1 % of the traded stony corals are bred. A crowbar and chisel are used to collect stony corals, resulting in the destruction of another part of the reef.