- A new study of major U.S.-based online retailers of marine fish bound for aquariums found that nearly 90% of traded species are sourced exclusively from the wild, including a number of threatened species, and that the trade is poorly tracked.
- The study raises concerns about the ecological impact of the trade on marine ecosystems, including around coral reefs, in countries such as Indonesia and the Philippines, where the fish are caught.
- Experts called for more work to develop sustainable fisheries and aquaculture in coastal communities in the Global South, and for building consumer awareness and establishing eco-certification schemes.
The United States is the main market for “ornamental” marine fish, those that end up as pets in aquariums. Now, a new study of U.S.-based online retailers has found that nearly 90% of traded species are sourced exclusively from the wild, including a number of threatened species, and that the trade is poorly tracked.
The study, published in October in the journal Conservation Biology, raises concerns about the ecological impact of the trade on marine ecosystems, including around coral reefs, in countries such as Indonesia and the Philippines, where the fish are caught.
“We urgently need stronger traceability and regulatory oversight to ensure that aquarium fish are sourced responsibly,” Bing Lin, a postdoctoral research associate at the University of Sydney, Australia, and lead author of the study, said in a press release. Lin undertook the study as a Ph.D. student at Princeton University, U.S. “Consumers have no reliable way of knowing whether the fish they buy were sustainably harvested.”
The study doesn’t deal with the trade in freshwater aquarium species, which have different supply chains and market dynamics, and are mainly bred in captivity. Nor does it look at the trade in sharks, invertebrates or corals — the focus is marine finfish.
More than 1,700 marine finfish species are traded internationally, according to a report by the secretariat of CITES, the global wildlife trade convention. Millions of individuals are traded across the world each year, many of them transported in plastic bags full of saltwater, with some dying en route. Such trade is generally legal unless CITES has instituted a ban for a particular taxon of fish.
The trade is not inherently unsustainable, but does pose a direct risk of depleting targeted fish populations and can also exert broader impacts, Lin said. For instance, the act of capturing marine finfish can damage coral reef ecosystems, such as when fishers use cyanide, a wide-acting poison, to flush fish out of crevices or stun them for easy capture. Additionally, the trade can facilitate the transfer of invasive species if pet fish are released in the wild or other marine organisms are accidentally brought along for the ride.
Lin and other members of his research team looked at four major U.S. retailers’ online offerings of marine finfish, and found 734 species for sale. Of those, 665, or around 89%, were always listed by retailers as being sourced from the wild, rather than from captive breeding (that is, aquaculture). The finding didn’t surprise experts, but it did help confirm, based on retail data, the prevalence of wild-sourced fish in the trade, which had previously been established using U.S. import and export data. Thirty-nine of the species, both wild-caught and captive-bred, were of conservation concern: 13 were listed as threatened by the IUCN, the global wildlife conservation authority, and another 26 had decreasing population trends.
Even “more interesting,” Lin told Mongabay, is that 282 of the 734 species, nearly 40%, were absent from at least one of the two main “authoritative databases” on the aquarium trade: one from the IUCN and the other from FishBase, the largest online database of finfish species.
“That’s a huge dearth in our knowledge because we know for a fact that these species are in the trade, given that from the point of retail, they’re available to be bought online,” Lin said. “So that’s problematic, and speaks to the opacity and lack of transparency and traceability within this trade.”
The study’s finding that dozens of species being traded are of conservation concern was alarming, according to Mariana Wong, a senior lecturer in marine sciences at the University of Wollongong in Australia. Wong, who wasn’t involved in the study, told Mongabay she was thankful it had brought the issue “once more into the spotlight” and was “getting people talking.”
Among other existing research on the marine aquarium trade is a 2023 paper in the journal Science Advances that ran risk assessments for traded species. It found, for example, that the popular but endangered Banggai cardinalfish (Pterapogon kauderni) is at high risk of being overexploited for the aquarium trade, as previous research had also indicated, with it long being considered one of the most problematic cases. The study included invertebrates, for which there’s even greater demand than finfish, lead author Gordon Watson, a professor of marine zoology at the University of Portsmouth in the U.K., told Mongabay.
The green chromis (Chromis viridis), which has iridescent turquoise scales, is the most commonly traded species in the United States and the European Union, according to Monica Biondo, head of research and conservation at the Switzerland-based Franz Weber Foundation, who’s been studying the marine ornamental fish trade since 2010. The green chromis’s IUCN status is “least concern,” based on a 2021 assessment, but its population is declining, making it one of the 39 species of conservation concern in Lin’s study.
Despite the risks that the trade can pose, it’s also a key source of income for some coastal communities in the Global South, so Lin, who’s from Indonesia, said it was important not to “vilify” it.
Lin and other experts who spoke to Mongabay for this article called for more work to develop sustainable fisheries and aquaculture in such coastal communities. Currently, most aquaculture for the aquarium trade takes place in Global North countries.
They also called for greater transparency and traceability in the supply chain, and for building consumer awareness and establishing eco-certification schemes. Finally, several experts raised the underlying need to address climate change to reduce the loss of coral reef ecosystems.
Watson said that if climate change isn’t contained, aquaculture could one day be the only option for the aquarium trade. Biondo, citing a new report on the “widespread dieback” warm-water coral reefs are undergoing, made similar remarks about the possible consequences of inaction.
“Without coral reefs there will also not be any fishes left!” she told Mongabay in an email. “Therefore, in fact all [marine ornamental fish] are threatened in my opinion.”
Banner image: Pyramid butterflyfish (Hemitaurichthys polylepis) around the island of Bali in Indonesia. Image courtesy of Bing Lin.
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Citations:
Lin, B., Zeng, Y., To, B., Holmberg, R. J., Rhyne, A. L., Tlusty, M., & Wilcove, D. S. (2025). Extent of threats to marine fish from the online aquarium trade in the United States. Conservation Biology. doi:10.1111/cobi.70155
Rhyne, A. L., Tlusty, M. F., Schofield, P. J., Kaufman, L., Morris, J. A., & Bruckner, A. W. (2012). Revealing the appetite of the marine aquarium fish trade: The volume and biodiversity of fish imported into the United States. PLOS ONE, 7(5), e35808. doi:10.1371/journal.pone.0035808
Watson, G. J., Kohler, S., Collins, J., Richir, J., Arduini, D., Calabrese, C., & Schaefer, M. (2023). Can the global marine aquarium trade (MAT) be a model for sustainable coral reef fisheries? Science Advances, 9(49). doi:10.1126/sciadv.adh4942
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