Of the almost 3,000 species of coral reef fishes caught worldwide [1], between 15 and 30 million animals are traded annually. [2]
Of the trade figures for the EU evaluated between 2014 and 2021, 30% of the fishes imported were not registered at species-level. [3] Therefore, it is inestimable which impact these removals have on the fish population and coral reefs. In 2018, almost 45 percent of all known coral reef fish species remained unassessed by the IUCN Red List due to a lack of biological and ecological knowledge. [8] Today, several hundered more species have been assessed but many species still have assessements which are more than 10 years old. [9] While the IUCN Red List provides the global conservation status of animal and plant species, it does not have the authority to grant legal protection.on.
The most frequently traded fishes are damselfishes (Pomacentridae) and wrasses (Labridae), which together account for almost half of all traded species. Other common families include angelfishes (Pomacanthidae), surgeonfishes (Acanthuridae), gobies (Gobiidae), and butterflyfishes (Chaetodontidae). [3][4]
ENDEMIC SPECIES – SMALL DISTRIBUTION AND SMALL POPULATIONS
Example: Banggai cardinalfish (Pterapogon kauderni)
The Banggai cardinalfish (Pterapogon kauderni) lives in small, isolated populations in shallow coral reefs and seagrass beds, often sheltering among sea urchins, coral heads, and anemones. The species has an extremely limited distribution, being endemic to just 23 km² in an archipelago off the coast of eastern Central Sulawesi, Indonesia. Within this area, its range is restricted to 34 of the 67 islands in the archipelago, 21 of which are under 6 km long. [5]
This fish exhibits unique biological and reproductive traits, including obligate commensalism with its hosts, sex-role reversal, and long incubation with advanced parental care — males brood 50–60 eggs and post-hatched embryos orally. Its low fecundity and lack of a larval phase result in strongly structured populations with distinct genetic signatures, making them highly vulnerable to overexploitation.
The Banggai cardinalfish has become a symbol of the challenges facing marine ornamental species — emblematic of the conflict between commercial exploitation and conservation. [5]
Discovered only in 1994, P. kauderni was classified as Endangered on the IUCN Red List in 2007, after more than 90% of its population had been extracted for the aquarium trade. Although the species can be successfully bred in captivity, wild capture remains cheaper, driving continued exploitation.
We collaborated in a study assessing the impact of international trade on the Banggai cardinalfish.
Despite its precarious status, two attempts to list the species under the CITES Appendices failed for political reasons:
In 2007, the United States of America proposed its inclusion in Appendix II to regulate and monitor trade. [6] In 2016, the European Union submitted a similar proposal. [7]
Both proposals were eventually withdrawn, leaving the species without international trade protection.
KEY SPECIES
Example: Common cleaner wrasse (Labroides dimidiatus)
The common cleaner wrasse (Labroides dimidiatus) performs a vital ecological role on coral reefs by cleaning parasites and dead tissue from other reef fishes, including sharks and rays. These interactions help maintain the health and balance of reef communities and make the species a keystone contributor to reef biodiversity.
Studies have shown that when cleaner wrasses are removed from a coral reef, other reef fish species begin to disappear within just four months, resulting in a significant loss of biodiversity. [8][9][10]
Despite their ecological importance, L. dimidiatus are extremely difficult to keep in captivity. They can only survive in highly species-rich aquariums, which is why even aquarium specialists advise against keeping them. [11]
ATTRACTIVE SPECIES
Example: Blue tang or blue surgeonfish (Paracanthurus hepatus)
In 2016, the blue tang (Paracanthurus hepatus) gained worldwide fame as the character “Dory” in the Walt Disney film Finding Nemo. [12] This exposure has made it a highly popular aquarium fish.
P. hepatus can grow up to 40 centimetres, which poses a challenge for conventional aquariums. Additionally, the species can behave aggressively toward other coral fishes, making it difficult to keep in community tanks.
Although breeding in captivity has been achieved, wild capture continues due to high demand. Fish advertised as “farmed” are often wild-caught juveniles that are then raised to market size in aquaria, rather than being bred over multiple generations in captivity. [13]
AGE SHIFTS
Example: Parrotfishes (Cetoscarus bicolor)
Juvenile parrotfishes are often targeted for capture because of their bright coloration or small size, which makes them more attractive and economical to transport. However, this practice threatens the sustainability of their populations. Removing too many juveniles alters the age structure of the species on the reef. If juvenile harvest is excessive, the adult population declines, as only a limited number of juveniles survive to maturity and contribute to replenishing the population. [14]
GENDER SHIFTS
Example: Mandarin fishes (Synchiropus splendidus)
Some populations of S. splendidus are already considered extinct in the wild. Their vivid coloration makes them highly sought after for the aquarium trade.
Because primarily males are targeted, the species’ population biology has been altered. Studies show that wild males now reach only 3 centimetres instead of the typical 6 centimetres, which is the optimal size for breeding. [15]
Mandarin fishes are usually harvested using hand spears, a method that can cause serious injuries or even death. [16]
FOOD
Example: Blue-green damselfishes (Chromis virdis)
C. viridis is the most traded coral reef fish in the world, with the United States alone importing nearly one million individuals annually. [4] Harvesting and transport cause high mortality rates. In the main exporting countries, Indonesia and the Philippines, these fish are often illegally caught using poison, which kills not only the damselfishes but also many other reef animals, and sometimes poisons the fishermen themselves. [17]
In our scientific research on the trade of marine ornamental fishes into the EU, we classified all traded species according to four key parameters:
- Number of specimens traded over a multi-year period
- Trend in trade volume (increase or decrease)
- Conservation status according to the IUCN Red List
- Vulnerability based on FishBase (www.fishbase.org)
Species categorized as “Not Evaluated” or “Data Deficient” in the IUCN Red List were excluded from this evaluation, as their conservation status could not be reliably assessed.
According to our 2019 study, we identified 17 species that were placed on a “watchlist”, indicating that these species may be threatened by international trade and should be closely monitored under CITES regulations.
In our latest peer-reviewed study (2024), we updated and refined these lists using eight years of EU trade data (2014–2021). This resulted in two classifications: “watchlist” and “watchlistPLUS”, the latter incorporating linear regression analyses to detect trends in trade volume more accurately. These updated tools provide a more precise assessment of species potentially at risk from the marine ornamental fish trade.
Watchlist of 2017
In our latest peer-reviewed study from 2024 we produced more accurate liste; a ‘watchlist’ and ‘watchlistPLUS’ (including linear regression) from 8 year of data from 2014 – 2021.
CAPTIVE BREEDING
Unlike freshwater ornamental fishes, where the majority are captive-bred, of the more than 2,300 coral fish species in trade, only about 25 species can be bred in captivity at commercial scale. For approximately 340 species, breeding success is still at the research stage. [18]
According to the United Nations, breeding coral fishes is challenging because their larvae require specialized diets and nutritional supplements that are difficult to replicate in captivity. As larvae mature, their dietary needs change, making wild capture a cheaper option than breeding. [5][19]
Example: Anemonefishes
After the Disney film Finding Nemo was released, demand for anemonefishes skyrocketed, leading to massive wild capture in eastern Australia, to the point that some populations have still not fully recovered. [20]
Although anemonefishes and seahorses are now bred in captivity, production cannot meet global demand, meaning the majority of anemonefishes in trade are still harvested from coral reefs. Because anemonefishes live in symbiosis with anemones, removing them disrupts anemone health and overall reef ecosystem stability. [21][22]