The journey from coral reef to aquarium: Every wild-caught coral reef fish kept in an aquarium has travelled a remarkable journey. For many species, this journey begins on a tropical coral reef and continues through a complex international supply chain involving collectors, local traders, holding facilities, exporters, airlines, importers, wholesalers and retailers before finally reaching a private or public aquarium. Depending on the destination, this journey may last from several days to several weeks. [1][2][3]
At every stage, fishes may experience handling, transport, confinement, environmental change and other stressors that influence both their survival and their welfare. [4][5]
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From reef to aquarium
Possible impacts along the journey include capture stress, habitat disturbance, repeated handling, deteriorating water quality, temperature fluctuations, disease, mortality and welfare impairment. [4][5]
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Collecting coral reef fishes
Most marine ornamental fishes are still collected directly from coral reefs using hand nets. Compared with destructive techniques such as cyanide fishing, hand-net collection is generally considered more selective and less directly damaging to reef habitat. However, it should not be described as harmless or impact-free. [1][2][6]
Capture may require collectors to pursue fishes into coral colonies, move coral rubble, disturb shelters and repeatedly visit the same collection sites. The ecological consequences depend on the biology of the target species, the intensity of collection, local reef condition, collector experience and the resilience of the population being harvested. [1][6][7]
Even where physical habitat disturbance is limited, the removal of fishes itself may affect reef ecosystems. Aquarium collection has been shown to affect local populations of target reef fishes in some locations, and species with small ranges, specialised habitat requirements, low reproductive output or important ecological roles may be especially vulnerable to repeated collection. [6][7][8]
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Cyanide fishing
(Suggested image: damaged coral, collection gear, or a neutral illustration of destructive collection.)
Although prohibited in many exporting countries for decades, cyanide fishing has not been eliminated. Collectors may spray a cyanide solution into coral crevices to stun fishes and make them easier to catch. [1][7][9]
The consequences extend beyond the target fishes. Cyanide can damage corals and other reef organisms, kill non-target animals and cause long-term physiological damage to fishes that survive the initial exposure. Collectors themselves may also be exposed to toxic chemicals during the process. [1][7][9]
Despite repeated international efforts to eliminate the practice, cyanide fishing has continued to be reported from parts of Southeast Asia, particularly Indonesia and the Philippines, which remain important exporting regions for marine ornamental fishes. [1][2][7][9]
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Holding and international transport
(Suggested image: fish packed in oxygenated plastic bags or export boxes.)
Following collection, fishes are transferred to local holding facilities where they are sorted, acclimated and prepared for export. Depending on export schedules and market demand, they may remain in holding facilities from several hours to several weeks. [1][4]
Before shipment, fishes are commonly fasted for approximately 24–48 hours to reduce waste production during transport. They are then packed individually or in small groups inside plastic bags containing seawater and oxygen. Water conditioners, antibiotics or sedatives may sometimes be used, although practices vary among exporters. [1][4][5]
The bags are placed inside insulated boxes designed to reduce temperature fluctuations during international flights. Depending on the destination and routing, fishes may remain in transport for more than 24 hours before reaching importers, wholesalers or retailers. [1][4]
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Deep-water species
(Suggested image: simple diagram showing slow decompression versus rapid ascent and swim bladder puncture.)
Some ornamental species are collected from deeper reefs. When fishes are brought rapidly to the surface, expanding gases inside the swim bladder may cause barotrauma. Experimental work on yellow tangs (Zebrasoma flavescens) in the marine ornamental aquarium fish trade has shown that decompression and venting can influence the signs of barotrauma and related stress responses. [10]
Slow ascent or decompression procedures are therefore important for reducing injury. In practice, rapid ascent may be followed by puncturing the swim bladder with a needle to release trapped gas. Although this may allow transport to continue, it causes injury, may increase the risk of infection and raises serious animal welfare concerns. [10]
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Mortality along the supply chain
One of the least understood aspects of the marine ornamental fish trade is mortality during capture, transport, holding, acclimation and after arrival in the final aquarium.
Published estimates vary considerably among species, collection methods, transport conditions and the parts of the supply chain investigated. Reported mortality ranges from only a few percent under well-managed conditions to more than 80% under poorly managed conditions or for particularly sensitive species. [4][5][11–20]
These differences should not be interpreted as contradictions. They reflect the extraordinary biological diversity of ornamental fishes, differences in capture and husbandry practices, and the fact that studies have measured mortality at different stages of the supply chain. Mortality may occur immediately after capture, during holding before export, during international transport, after import, in wholesale or retail facilities, or following introduction into the final aquarium. [4][5][11–20]
Importantly, collected fishes that die or are rejected before export, sale or final reporting may go unrecorded. Recorded trade volumes may therefore underestimate the number of fishes removed from the wild. [20]
Despite decades of concern, no comprehensive monitoring system currently records mortality throughout the entire marine ornamental fish supply chain. Consequently, no robust global estimate exists for cumulative mortality associated with the trade. Recent scientific reviews continue to identify this as a major knowledge gap in evaluating sustainability and welfare. [4][5][19][20]
Understanding where and why mortality occurs is essential for evaluating both the biological impact of the trade and the welfare implications for individual fishes. It also provides the scientific basis needed to assess claims about sustainability.
What science still does not know
- Global cumulative mortality from reef to aquarium
- Species-specific mortality and welfare risks
- Mortality after import and during retail holding
- Long-term survival in the final aquarium
- Where in the supply chain the greatest losses occur
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Fish welfare
For many years, discussions surrounding the marine ornamental fish trade focused mainly on conservation and trade monitoring. Today, there is growing recognition that the welfare of individual fishes also deserves careful consideration. [4][5][11]
Scientific understanding of fishes has changed profoundly over the past two decades. Research has demonstrated sophisticated cognition, learning, long-term memory, social recognition and behavioural flexibility in fishes. The popular idea that fishes possess only a “three-second memory” has been thoroughly disproven. [21][22]
There is now strong scientific evidence that fishes are sentient vertebrates whose welfare deserves ethical and practical consideration. Fishes possess nociceptors, show complex physiological and behavioural responses to injury, and experience stress, fear and pain. [21][23–26]
Throughout capture, holding and transport, fishes may experience repeated confinement, injuries, food deprivation, deteriorating water quality, temperature fluctuations, disease risk and prolonged transport. These stressors may compromise both survival and welfare. [4][5][11]
Better monitoring throughout the supply chain is therefore essential. It helps identify where unnecessary mortality and suffering occur, and it provides the scientific information needed to evaluate the full consequences of the marine ornamental fish trade for both wild populations and individual animals.
Every coral reef fish collected from the wild is an individual living animal. Understanding what happens during its journey from reef to aquarium is essential for evidence-based conservation, informed policy and responsible consideration of animal welfare.
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References
[1] Wabnitz, C., Taylor, M., Green, E. & Razak, T. (2003). From Ocean to Aquarium: The Global Trade in Marine Ornamental Species. UNEP-WCMC. https://digitallibrary.un.org/record/505321/files/fromoceantoaquar03wabn.pdf
[2] Cohen, F.P.A., Valenti, W.C. & Calado, R. (2013). Traceability Issues in the Trade of Marine Ornamental Species. Reviews in Fisheries Science, 21(2), 98–111. https://www.tandfonline.com/doi/abs/10.1080/10641262.2012.760522
[3] Monticini, P. (2010). The Ornamental Fish Trade: Production and Commerce of Ornamental Fish. FAO GLOBEFISH Research Programme, Vol. 102. https://openknowledge.fao.org/server/api/core/bitstreams/b02939ef-3536-4e8e-be33-2524d8452738/content
[4] Stevens, C.H., Croft, D.P., Paull, G.C. & Tyler, C.R. (2017). Stress and welfare in ornamental fishes: what can be learned from aquaculture? Journal of Fish Biology, 91, 409–428. https://doi.org/10.1111/jfb.13377
[5] Maia, C.M., Gauy, A.C.d.S. & Gonçalves-de-Freitas, E. (2025). Fish Welfare in the Ornamental Trade: Stress Factors, Legislation, and Emerging Initiatives. Fishes, 10(5), 224. https://www.mdpi.com/2410-3888/10/5/224
[6] Dee, L.E., Horii, S.S. & Thornhill, D.J. (2014). Conservation and management of ornamental coral reef wildlife: successes, shortcomings, and future directions. Biological Conservation, 169, 225–237. https://doi.org/10.1016/j.biocon.2013.11.025
[7] Thornhill, D.J. (2012). Ecological Impacts and Practices of the Coral Reef Wildlife Trade. Defenders of Wildlife.
https://defenders.org/sites/default/files/publications/ecological-impacts-and-practices-of-the-coral-reef-wildlife-trade.pdf
[8] Tissot, B.N. & Hallacher, L.E. (2003). Effects of aquarium collectors on coral reef fishes in Kona, Hawai‘i. Conservation Biology, 17(6), 1759–1768. https://doi.org/10.1111/j.1523-1739.2003.00379.x
[9] Mak, K.K.W., Yanase, H. & Renneberg, R. (2005). Cyanide fishing and cyanide detection in coral reef fish using chemical tests and biosensors. Biosensors and Bioelectronics, 20(12), 2581–2593. https://doi.org/10.1016/j.bios.2004.09.015
[10] Munday, E.S., Tissot, B.N., Heidel, J.R. & Miller-Morgan, T. (2015). The effects of venting and decompression on yellow tangs Zebrasoma flavescens in the marine ornamental aquarium fish trade. PeerJ, 3, e756. https://doi.org/10.7717/peerj.756
[11] Huntingford, F.A., Adams, C., Braithwaite, V.A., Kadri, S., Pottinger, T.G., Sandøe, P. & Turnbull, J.F. (2006). Current issues in fish welfare. Journal of Fish Biology, 68(2), 332–372. https://doi.org/10.1111/j.0022-1112.2006.001046.x
[12] Cato, J.C. & Brown, C.L. (eds.) (2003). Marine Ornamental Species: Collection, Culture and Conservation. Wiley-Blackwell. https://doi.org/10.1002/9780470752722
[13] Gasparini, J.L., Floeter, S.R., Ferreira, C.E.L. & Sazima, I. (2005). Marine ornamental trade in Brazil. Biodiversity and Conservation, 14, 2883–2899. https://doi.org/10.1007/s10531-004-0222-1
[14] Yeeting, B. (2010). Developing a sustainable marine aquarium trade industry on Kiritimati Island. SPC Fisheries Newsletter, 131.
https://www.meripmicronesia.org/wp-content/uploads/2012/01/Fisheries-Newsletter-2010.pdf
[15] Vagelli, A.A. (2011). The Banggai Cardinalfish: Natural History, Conservation, and Culture of Pterapogon kauderni. Wiley-Blackwell. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1095-8649.2012.03297.x
[16] Conant, T.A. (2014). Endangered Species Act Draft Status Review Report: Banggai Cardinalfish, Pterapogon kauderni. NOAA/NMFS.
https://repository.library.noaa.gov/view/noaa/17086
[17] Livengood, E.J. & Chapman, F.A. (2007). The Ornamental Fish Trade: An Introduction with Perspectives for Responsible Aquarium Fish Ownership. University of Florida IFAS Extension, FA124.
https://extension.rwfm.tamu.edu/wp-content/uploads/sites/8/2013/10/The-Ornamental-Fish-Trade-An-Introduction-with-Perspectives-for-Responsible-Aquarium-Fish-Ownership.pdf
[18] Rubec, P.J. & Cruz, F.P. (2005). Monitoring the chain of custody to reduce delayed mortality of net-caught fish in the aquarium trade. SPC Live Reef Fish Information Bulletin, 13, 13–23. https://www.spc.int/DigitalLibrary/Doc/FAME/InfoBull/LRF/13/LRF13_13_Rubec.pdf
[19] Biondo, M.V., Burki, R.P., Aguayo, F. & Calado, R. (2024). An Updated Review of the Marine Ornamental Fish Trade in the European Union. Animals, 14(12), 1761. https://doi.org/10.3390/ani14121761
[20] Militz, T.A., Foale, S., Kinch, J. & Southgate, P.C. (2016). Fish Rejections in the Marine Aquarium Trade: An Initial Case Study Raises Concern for Village-Based Fisheries. PLOS ONE, 11(3), e0151624. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151624
[21] Brown, C. (2015). Fish intelligence, sentience and ethics. Animal Cognition, 18, 1–17. https://doi.org/10.1007/s10071-014-0761-0
[22] Brown, C., Laland, K. & Krause, J. (eds.) (2011). Fish Cognition and Behavior (2nd edition). Wiley-Blackwell. https://researchers.mq.edu.au/en/publications/fish-cognition-and-behavior-2/
[23] Sneddon, L.U. (2003). Do fishes have nociceptors? Evidence for the evolution of a vertebrate sensory system. Proceedings of the Royal Society B, 270, 1115–1121. https://doi.org/10.1098/rspb.2003.2349
[24] Sneddon, L.U. (2015). Pain in aquatic animals. Journal of Experimental Biology, 218, 967–976. https://doi.org/10.1242/jeb.088823
[25] Sneddon, L.U. (2019). Evolution of nociception and pain: evidence from fish models. Philosophical Transactions of the Royal Society B, 374, 20190290. https://doi.org/10.1098/rstb.2019.0290
[26] Braithwaite, V.A. (2010). Do Fish Feel Pain? Oxford University Press. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1095-8649.2011.03007.x