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Pilot program tries to get U.S. aquariums to raise their own fish, not catch them

Clownfish can reportedly lay clutches of over 1000 eggs.

Clownfish can reportedly lay clutches of over 1000 eggs. Image by Roger Williams University.

  • A collaboration between the New England Aquarium in Massachusetts and Roger Williams University in Rhode Island has developed protocols for breeding marine aquarium fish, including five species never before raised in captivity.
  • Though some fisheries for ornamental fish are responsibly managed and benefit local economies, harmful collection practices like cyanide fishing and overcollecting can harm ecosystems.
  • Aquaculture of ornamental fish can improve fish welfare, reduce the spread of disease, take the guesswork out of fish sourcing, and reduce impacts on wild populations.

While at university studying chemical ecology and aquaculture, Andy Rhyne picked up a job at an aquarium shop to raise money for a cross-country bike trip. Though he didn’t know it at the time, the gig would lead him to an important observation and, eventually, a place on an innovative team working to change how aquariums obtain fish.

“I could really see very quickly that there was not a lot of aquaculture in the marine aquarium industry,” said Rhyne, now an associate professor of marine biology at Roger Williams University in Bristol, Rhode Island.

Rhyne convinced his supervisor to start stocking aquacultured clownfish (Amphiprioninae spp.), one of the only groups of marine fish being bred in captivity at the time. He noticed that unlike the fragile wild clownfish, these individuals were robust — even friendly.

“They would come eat out of your fingers,” Rhyne told Mongabay on an early morning video call from his office at the marine lab in Bristol, where he now runs a successful breeding program for marine fish. “You could sell those fish to [a new hobbyist], and they could keep those fish alive.”

Despite the hour, Rhyne was energized, gesturing enthusiastically in front of a large painting of a queen triggerfish (Balistes vetula), a gift from a student. In 2009, teams from Roger Williams University and the New England Aquarium in Boston, Massachusetts, working as the Larval Fishes Aquaculture Program, successfully reared adult queen triggerfish in captivity for the first time ever. So far, the collaboration has reared 17 species of fish, including five never before raised in captivity: the blue chromis (Chromis cyanea), brown chromis (C. multilineata), glassy sweeper (Pempheris schomburgkii) and queen triggerfish.

More than 90% of ornamental fish in the aquarium trade, an industry worth up to $30 billion, are freshwater species, and most of those are bred rather than collected, according to a 2019 paper in the Journal of Fish Biology. However, most marine species are still caught from the wild. Depending on the sustainability of the operations, these ornamental fisheries can harm the environment and fish populations.

Glassy sweepers are also sometimes called copper sweepers for their copper-colored scales. Image courtesy of the New England Aquarium.
A vibrant red shrimp reared at the wet laboratory and breeding facility at Roger Williams University. Image courtesy of Roger Williams University.

The challenges of marine fish

Barbara Bailey, a 37-year veteran of the New England Aquarium, recalled when the facility’s Giant Ocean exhibit was the largest tank in the U.S., holding 200,000 gallons, or 909,000 liters. Now dwarfed by more modern tanks at other aquariums, the exhibit is still spacious enough to encourage fish to spawn in captivity. Staff collect those eggs and transport them to the Roger Williams University marine lab, where Rhyne’s team begins the challenging process of rearing them from eggs to adults.

Aquaculture takes on a new level of complexity when dealing with marine fish: unlike freshwater fish, which have relatively simple breeding systems, marine fish rely on variables like currents and ocean temperatures to tell them when to breed. Even if experts can create the right conditions, marine fish are challenging to raise. Having the right food for the fish is crucial.

“You can’t be successful with a larval program if you don’t have the food,” Bailey said. “That’s the frustrating part: figuring out exactly what they need at that milestone developmental stage.”

The Giant Ocean tank at the New England Aquarium was once the largest aquarium tank in the United States. Image courtesy of the New England Aquarium.

The group now produces food in-house, for example making sure they have various sizes of fish favorites like mysid shrimp (Mysida spp.).

Bailey and her team collaborate with the Rhyne lab to identify species that are good candidates for aquaculture, looking at factors including the conditions of the native wild fishery and how the fish respond to stress.

One of the collaboration’s major successes is the glassy sweeper, a native of the deep-water reefs in the Caribbean. Wild-caught glassy sweepers respond poorly to transport and become skittish when on exhibit, showing signs of stress. Reminiscent of the clownfish of Rhyne’s youth, the captive-reared glassy sweepers are bolder, forming beautiful schools that reflect their behavior in the wild.

“They live under ledges and in caves, and they’re copper-colored,” Bailey said. “They go in and out of the light. And it’s just beautiful when you see that.”

Mesmerizing to watch, the fish draw in visitors and help teach the public about the importance of coral reefs. “The glassy sweeper is a key species to make that exhibit really dynamic,” Bailey added.

Clownfish are one of the most popular marine aquarium fish among hobbyists. Although their popularity is often attributed to the Disney Movie Finding Nemo, these charismatic fish have been bred in captivity since the 1970s. Image courtesy of Roger Williams University.

Advantages of aquaculture

While aquaculture can be challenging, harvesting from wild populations isn’t easy either, and it comes with a host of potential sustainability issues.

Aquariums transport wild-caught fish in water-filled enclosures by airplane, making the method significantly more carbon intensive. If the trip from ocean to tank takes too long, fish can become stressed, and can even die. Once the fish arrive at their new home, they must be quarantined to avoid the spread of parasites. Captive-bred fish raised from eggs can skip this step because they come from a known location — something that isn’t always a given in the ornamental fish trade.

“Knowing where your fish come from is important because you want to make sure that they’ve been acquired ethically, sustainably and responsibly,” Bailey said.

Ornamental fish supply chains can be difficult to track due to a lack of monitoring infrastructure. This means even highly resourced aquariums may inadvertently purchase fish that were unsustainably collected. Before the pandemic interrupted operations, Bailey and her team would sometimes oversee collection missions personally to ensure attention to sustainable collecting and fish welfare.

In addition, harmful collecting practices can tax ecosystems already struggling with overfishing, coral bleaching, warming waters, and other climate change impacts. Cyanide fishing, a practice commonly used in Southeast Asia, can be especially devastating: local fishers stun the fish with sprayed sodium cyanide before packing them tightly with other fish in bags for shipping. The poor conditions and the lingering effects of the cyanide poisoning can result in high mortality rates, not to mention the damage caused to the remaining fish populations in the reefs.

Juvenile fish swim in tanks at the wet laboratory and breeding facility at Roger Williams University. Image courtesy of Roger Williams University.
Aquarium staff at the New England Aquarium prepare to move glassy sweepers to a different facility. Image courtesy of the New England Aquarium.

Local economies

Even so, the issue isn’t as simple as banning wild capture of ornamental fish, according to experts from the Larval Fishes Aquaculture Program and other groups.

“Sometimes you take away societal benefits [when you ban aquarium fishing],” said Michael Tlusty, associate professor of sustainability and food solutions at the University of Massachusetts Boston, who also collaborates with the Larval Fishes Aquaculture Program. “A lot of times, if those societies need an intact ecosystem, you also get that ecosystem preservation.”

If implemented correctly, wild harvesting of fish for the aquarium trade could actually be a boon for both local fishers and conservation, providing economic opportunity and incentivizing responsible management of precious fish stocks in the process. Tlusty said. Ornamental fish fetch far higher prices per individual fish than those destined for the dinner plate, reducing the hours that fishers need to work to sustain their families. For some communities, the aquarium trade may be the only environmentally friendly income stream, according to Tlusty. Removing this option could force young people to search for work in urban areas, devastating their communities both financially and culturally.

Brian Tissot, director of the Humboldt State University Marine Laboratory, said increasing training and regulation in small-scale ornamental fisheries may be a promising way to maintain the industry for local people while discouraging harmful practices.

Glassy sweepers school in an off-exhibit tank. Image courtesy of the New England Aquarium.

Studying ornamental fisheries in the waters off western Hawai‘i in the late 2000s, Tissot’s team helped establish fishing replenishment areas (FRAs) and marine protected areas (MPAs) to ensure sustainable stocks of desirable fish like the yellow tang (Zebrasoma flavescens). They also monitored the sustainability of local harvesting practices. Despite Tissot’s data showing that proper management of these fisheries had brought populations of commonly collected aquarium fish to sustainable levels, even with ongoing collecting, Hawai‘i’s Department of Land and Natural Resources has since banned the trade following litigation by opponents of aquarium fishing. The ban will remain in effect unless the fisheries complete an environmental review process.

“There’s a lot of people that are just against the very idea that you’re capturing a live fish and you’re shipping it off somewhere,” Tissot said. “It’s based on ethical beliefs. And I think it’s [an] entirely valid perspective.”

Tissot, who is not involved in the Larval Fishes Aquaculture Program, said he believes a full transition to captive-bred ornamental marine fish is unlikely. However, he noted the importance of the new techniques being developed by Roger Williams University and the New England Aquarium, saying they would become an important part of a well-rounded plan to ensure more sustainable practices in the aquarium industry, building on existing strategies like MPAs and responsible wild collecting efforts. He suggested that such techniques could spread far beyond aquariums in the U.S.

“Ultimately, what you want to do is develop those techniques for aquaculture in the source countries,” he said.

Weedy sea dragons (Phyllopteryx taeniolatus) cling to a piece of their enclosure. The program has yet to successfully breed the species in captivity, but doing so remains a major goal of the Larval Fishes Aquaculture program. Image courtesy of the New England Aquarium.

Spreading the wealth

Back in Rhode Island, the Roger Williams University and New England Aquarium teams are already working to share their hard-earned expertise with other aquariums, although so far only those in the U.S. Supported by the Disney Conservation Fund and the Aquatic Collection Sustainability Fund of the Association of Zoos and Aquariums, the group has hosted workshops to teach 21 peer aquariums to culture their own fish. After each workshop, the Larval Fishes Aquaculture Program ships small starter equipment to the facilities to get new breeding programs off the ground.

All of the aquarists interviewed for this story agreed on one point: having the right fish in the right exhibit can make all the difference when trying to grasp the ephemeral attention of a public unfamiliar with the complexities of the world’s oceans. Charismatic fish like the leafy seadragon (Phycodurus eques) are far more than a curiosity: they can open the door for a conversation.

“If you show people a tank of algae, you’re going to get them for about half a second. And they’re going to walk away,” Rhyne said. “That display of the kelp forest is made by [the leafy seadragon] in there because people will watch that fish for half a day. You can talk to them about kelp and climate and the need to maintain these ecosystems for this amazing fish.”

Bailey and Rhyne plan to continue to grow the program by supplying fish to participating institutions, which then make a contribution back to the Aquatic Collection Sustainability Fund.

“We want to look at the entire supply chain of aquarium fish,” Rhyne said. “And we want to view it holistically and acquire species either from ethical sources in the wild or from aquaculture: that really helps aquariums continue their mission of education and conservation.”

A student adjusts equipment at the wet laboratory and breeding facility at Roger Williams University. Image courtesy of Roger Williams University.

Banner image: Clownfish can reportedly lay clutches of over 1000 eggs. Image by Roger Williams University.


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Evers, H.-G., Pinnegar, J. K., & Taylor, M. I. (2019). Where are they all from? – sources and sustainability in the ornamental freshwater fish trade. Journal of Fish Biology, 94(6), 906-916. doi:10.1111/jfb.13930

Militz, T. A., & Foale, S. (2017). The “Nemo Effect”: Perception and reality of Finding Nemo‘s impact on marine aquarium fisheries. Fish and Fisheries, 18(3), 596-606. doi:10.1111/faf.12202

Rhyne, A. L., Tlusty, M. F., & Kaufman, L. (2014). Is sustainable exploitation of coral reefs possible? A view from the standpoint of the marine aquarium trade. Current Opinion in Environmental Sustainability, 7, 101-107. doi:10.1016/j.cosust.2013.12.001

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