In any given year, millions of brightly colored marine fish journey thousands of miles from their natural habitats in tropical waters to pet stores and home aquariums in the United States.

Most of the saltwater fish caught in the wild die before they get to dentist offices or living rooms. A Mystic Aquarium researcher is working to shorten that journey and bring down the mortality rate by figuring out how to breed them in labs.

There are many reasons why researchers have struggled to make aquaculture breeding a bigger part of the marine aquarium industry, which researchers think brings more than 11 million individual fish, representing nearly 2,000 species, into the U.S. every year, said Paul Anderson, a research scientist at the Aquarium.

One is particularly confounding.

"Fish have really weird sex lives," he said.

Mystic Aquarium researchers have spent the last three years trying to create the ideal romantic conditions for royal grammas, working out of a lab at the Marine Science Magnet High School in Groton.

The species, popular in saltwater aquariums, breed when the male fish builds a nest out of algae for the female fish, which deposits between 20 and 100 eggs. The fish don't develop separate sex characteristics until well after they hatch, becoming male or female as juveniles based on unknown environmental factors. They also often eat their own eggs if they sense something that could endanger the larvae.

Behind a dark curtain in the magnet school's lab — "for privacy," Aquarium research assistant Vince Vacco said — a dozen bright yellow and purple fish float in individual tanks.

Anderson and two other Mystic Aquarium researchers are about to embark on the third trial of an effort that began in 2016 to hatch royal gramma eggs in the lab and grow them into fish, a multi-stage process that requires minute attention to the fishes' food, water temperature, light and tank setups, all of which could mean the difference between more dead grammas or a major shift in the way tropical species are bred in captivity.

The project is funded by Connecticut Sea Grant and Rising Tide Conservation, a collection of research labs, public aquaria, and businesses working to build up a bigger supply of ornamental fish raised in aquaculture facilities.

Pressure from consumers and new regulations have pushed the aquarium fish industry in a more sustainable direction, said Eric Litvinoff, the magnet school's director of aquaculture.

"Now we're starting to see hobbyists are starting to ask the question: 'Where did the fish come from?'" he said. "People are saying, 'Oh, it would be nice if it was aquacultured.'"

But destructive practices persist: Fishermen catch many popular aquarium species in their natural habitats using cyanide or dynamite to temporarily stun the fish before selling them to a distributor.

Before the fish arrive at U.S. pet stores, where they're sold for anywhere from $6 to $150 per fish, many die from infection, parasites or lingering effects of their capture, sometimes not until a buyer takes them home.

"There's a lot of mortality along the way," Anderson said. "And there's no disincentive for importing fish with poor health."

Royal grammas scarce

Research institutions and aquaculture companies have had some success replacing the wild-caught fish industry with fish bred in labs. Rising Tide Conservation boasts success supporting the breeding of yellow and blue tang — think Dory from "Finding Nemo" — jackknife fish and the neon-colored green chromis, among about a dozen other species.

Most clownfish, which are easy to breed and hugely popular in the United States, are now bred in captivity, according to Jeremy Reynolds, the owner of Shoreline Pet & Aquarium in Old Saybrook.

And there's a market for more species coming from aquaculture facilities instead of coral reefs, Reynolds said.

"They sell well, and I can get a wide variety of different colors and patterns," he said. "All of us would love if every saltwater fish was captive bred."

But supply is low for captive-bred royal grammas, and scarcity means they're too expensive for even the most avid aquarium owners.

"There's no one really out there selling a lot of captive-bred royal grammas — I don't know anyone who's doing it," Reynolds said. "It has not been economically feasible." 

Royal grammas, which face threats in their natural habitat including polluted water and predatory lionfish, are an ideal candidate for aquaculture, said Judy St. Leger, a vice president at SeaWorld and the president of Rising Tide Conservation.

"It's not a fish that can't be bred in captivity," she said. "There are currently aquacultured royal grammas that can be purchased on the market — but there's not enough to meet the market demand."

The fish can be hard to please. Anderson said he believes the fish in the first two trials of the project ate their own eggs before they could hatch, possibly because they sensed a threat.

Recreating the ideal conditions for raising ornamental fish already on the market required plenty of trial and error, St. Leger said.  

"We've already overcome the No. 1 challenge — it was a lot of people saying, 'you can't do this,'" St. Leger said. "(Then) we simply had to learn how to mate these fish, how to feed them correctly ... and then how to raise the babies. Every one of those steps is a major hurdle."

With Vacco and other Aquarium staff, Anderson is working on a new method for collecting eggs that will keep the fish from eating them before they can hatch.

The fish that will make up the third trial have been quarantined in a large tank in the school's aquaculture lab for more than a month while the researchers treat them for any infections or parasites they may have acquired in the wild.

In addition to using the lab at the school for the breeding trials, the Mystic Aquarium team has presented its research to the school's marine biology students and involved them in the project.

The partnership between the aquarium and the school allows the students to watch research with real-life implications and could teach more young people about the problems plaguing the aquarium industry. Interns who have worked with Anderson on the project have gone on to work either in the aquarium industry, enroll in graduate aquaculture programs or decide to become teachers themselves.

"You get more people getting into the industry who know how to take care of fish, you're going to have less mortality," he said.

The ethical choice

On Tuesday, Vacco and Kelsey Moon, an aquarium intern, leaned over a royal gramma they had scooped out of the tank it shares with 15 others.

The fish struggled for a few minutes against the effects of a sedative, then stopped moving. Vacco quickly took its measurements.

"Length: 3.7," he said, while Moon scribbled on a clipboard. "Depth: 1.2."

They spent Tuesday separating the fish by sex: the ones that grow to more than 2.5 centimeters are males, and get marked with a small dot of white dye and elastic injected under their scales. Anything smaller than that could be male or female, but are counted as female for efficiency's sake.

Later they'll be paired up in individual tanks for the third round of breeding trials, which Anderson said he hopes will generate fertilized eggs and larvae.

He said he's confident a market exists for captive-bred royal grammas, if only researchers can develop a way to produce the fish on a commercial scale. Captive-bred fish cost more, but many consumers see them as the more ethical choice.

"People will pay a premium for organic food, because they see it as higher quality..." Anderson said. "It's a matter of the will of the people to make that paradigm shift."

m.shanahan@theday.com