Cyanide fishing is a method employed to capture marine fish alive on coral reefs. They are shipped to markets for human consumption in Southeast Asia, as well as to supply the marine aquarium trade worldwide. Although several techniques can be used to detect cyanide in reef fish, there is still no testing method that can be used to survey the whole supply chain. Most methods for cyanide detection are time-consuming and require the sacrifice of the sampled fish. Thiocyanate anion (SCN−) is a metabolite produced by the main metabolic pathway for cyanide anion (CN−) detoxification. Our study employed an optical fiber (OF) methodology (analytical time <6 min) to detect SCN− in a non-invasive and non-destructive manner. Our OF methodology is able to detect trace levels (>3.16 µg L−1) of SCN− in seawater. Given that marine fish exposed to cyanide excrete SCN− in the urine, elevated levels of SCN− present in the seawater holding live reef fish indicate that the surveyed specimens were likely exposed to cyanide. In our study, captive-bred clownfish (Amphiprion clarkii) pulse exposed for 60 s to either 12.5 or 25 mg L−1 of CN− excreted up to 6.96±0.03 and 9.84±0.03 µg L−1 of SCN−, respectively, during the 28 days following exposure. No detectable levels of SCN− were recorded in the water holding control organisms not exposed to CN−, or in synthetic seawater lacking fish. While further research is necessary, our methodology can allow a rapid detection of SCN− in the holding water and can be used as a screening tool to indicate if live reef fish were collected with cyanide.

The marine ornamental fish trade (MOFT) is a worldwide industry that targets a remarkable quantity and diversity of reef fish species and provides an important source of revenue for exporting countries, particularly developing nations in Southeast Asia. Here we provide, for the first time, an economic assessment of the MOFT to the European Union (EU), one of the key players of the marine aquarium trade, along with the USA and Japan. Data from EUROSTAT (the European Statistical System) was analysed for the MOFT between 2000 and 2011. Results show that this industry was not affected by the economic crisis and accounted for a total of 135 million Euros during the study period. Both the UK and Indonesia have been reinforcing their importance as leading importer and exporter countries, respectively. The long-term temporal pattern of the MOFT by EU and non-EU countries is described, as well as its diversity and evenness between importing and exporting countries. The present economic assessment also identifies the key players of this industry, and ultimately contributes to management and conservation practices that may enhance the sustainable use of world's coral reefs.

The illegal use of cyanide poisoning to supply live reef fish to several markets is one of the main threats to coral reefs conservation in the Indo-Pacific. The present study performed the first survey ever monitoring the marine aquarium trade in the EU for the presence of physiological evidence consistent with cyanide poisoning in live reef fish. This survey was also the first one worldwide employing a non-invasive sampling approach. Nearly 15% of the fish screened displayed physiological evidence of being illegally collected using cyanide poisoning (by testing positive for the presence of the thiocyanate anion (SCN−) in their urine). The efforts promoted so far to completely eradicate cyanide caught fish from the marine aquarium trade have not been effective, as our results suggest that their prevalence in the trade is in line with data reported nearly two decades ago. A new paradigm is urgently needed to effectively ban cyanide caught fish from the marine aquarium trade.

Cyanide fishing is one of the most destructive techniques employed to collect live reef fish. While national laws of most source countries ban this practice, cyanide is still widely employed to capture live reef fish for human consumption and marine aquariums. The United States is one of the largest importers of live reef fish, and the implementation of new approaches to screen for fish caught with cyanide is urgently needed. A fast and reliable noninvasive and nondestructive approach to screen live reef fish for cyanide poisoning was recently developed, yet deployment of this test may be obstructed by U.S. law. The Lacey Act prohibits the import, export, transport, and acquisition in interstate or international commerce of fish taken in violation of any foreign law. Therefore, if a fish tests positive for cyanide poisoning, the testers could expose themselves to liability for potential Lacey Act violations, as they are "knowingly" engaging in an illegal act. To eliminate this disincentive, the U.S. government should help conservationists develop protocols on how to test for cyanide poisoning without violating the Lacey Act.