By Emma Fass, Summer Science Writing Intern
While many people love to have beautiful, decorative fish swimming in their saltwater tanks at home, they may not realize that, before these pets were marine ornamentals, many were wild fish. And just like commercial fishing, capturing or harvesting wild fish for aquariums has an effect on fish populations.
Adding new fish to a saltwater aquarium may be getting more sustainable, however, thanks to researchers at the Virginia Tech-Virginia Seafood Agricultural Research and Extension Center (VSAREC) in Hampton.
“We want to reduce pressure on wild marine ornamental species by having economically available tank-raised fish,” says Mike Schwarz, aquaculture specialist and head of the VSAREC aquaculture program.
To achieve that goal, researchers have to figure out how to breed and raise these fish larvae in tanks. And because every fish is different, developing the methods, feed, and protocols to bring tank-raised fish to market takes time and testing.
In the spring of 2015, Virginia Sea Grant affiliated staff at the lab launched a conservation aquaculture initiative focused on using aquaculture to meet some of the demand for aquarium fish, reducing the pressure on wild fish populations.
“We can make a direct difference on some of the fishing pressures even if it’s just on a species-by-species basis,” says Schwarz.
With the exception of clownfish, the vast majority of marine aquarium fish on the market today are harvested rather than tank-raised. The harvested fish found for sale in the United States tend to come from countries where fishing regulations may be difficult to enforce over extensive rural areas. Other stocks are threatened or endangered by environmental degradation.
The U.S. imports about 11 million aquarium fish from about 2,000 species a year—a potential opportunity for American businesses to raise and sell the fish instead. Consumers also often prefer tank-raised aquarium fish due to the environmental impact of harvesting wild fish.
“If you go into any pet store, consumers prefer the fish that are labeled tank-raised or something similar, even when they are more expensive,” says Schwarz.
For nearly two decades, Virginia Tech researchers have been conducting research on marine food fish larvae culture. The VTASREC lab has developed protocols for raising flounder, striped bass, spadefish, cobia, pompano, and tilapia, among others. It’s also working with red porgy and yellowtail.
“Now we’re just correlating and applying that same expertise to marine ornamentals,” says Schwarz.
One difference between the two types of aquaculture is the equipment. When dealing with food fish, the adults are the size of a hand or larger and have to be kept in huge tank systems with fast running water. The section of the lab focused on marine ornamentals consists instead of walls and walls of orange, blue, and purple fish darting through their tanks, in and out of structures such as PVC pipe or flower pots.
Steve Urick, VT-VSAREC hatchery manager, says that the lab is working with four types of marine ornamentals this year: clownfish, neon goby, orchid dottyback, and flame angels.
“Clownfish are referred to in the lab as the bread-and-butter of ornamentals,” says Urick. “Thanks to the movie Finding Nemo, they’re popular in pet stores because they are recognized and loved by just about every child.”
Clownfish are also among the simplest to raise. Their big larvae that can eat larger morsels of food and metamorphose quickly, transitioning from larvae to fry in about two weeks.
Hobbyists like neon gobies because they are colorful and they preen other fish, feasting on any parasites on the other fish’s skin. The brilliant color of orchid dottybacks attracts buyers and has a higher market value.
With these adult fish in house, the next step is spawning. For ornamentals, it’s a difficult process. They need to spend time together before they court and pair off, often for life. Some also reverse gender. Orchid dottybacks start out as female, but they can become male. Clownfish start out as males, but the larger, more dominant fish within a pair becomes a female.
Fish don’t always get along, however, in the getting-to-know-you stage. “So until they want to, you just try to provide the best environment,” says Schwarz. He adds with a laugh, “and the best mood lighting. It’s a lot of getting everything right and then waiting.”
Once spawning begins, the researchers must deal with egg incubation, larvae culture, husbandry, developing baseline protocols, and optimizing the entire process. From raising the larvae, which has proven to be a challenge, to producing new adults, the process is complicated and time-consuming.
Considering the hundreds of marine food fish and ornamentals that still require study in order to effectively ways raise them in tanks, Schwarz says he sees this research continuing for the foreseeable future. Given its economic and environmental advantages, however, he believes the work is well worth it.
“Through the technologies that we’re producing we hope to allow more people to access the knowledge to be able to get into the industry,” says Schwarz. “Both personally and programmatically, we are trying to make the world a better place,” he says. “Species diversity and the health of the oceans are paramount issues to our program.”
